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Solar Sun Tracker PVCOOL 4m2 BP Kyocera Sharp Suntech |  |
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US $446.49 | 44m |
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Solar Tracking System ST 6 DIY kit suit for any panels | |
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US $536.69 | 44m |
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MP3 KIDS RIDE ON R C CAR REMOTE CONTROL POWER WHEELS RC | |
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US $184.95 | 49m |
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100w JL Mono Solar Panel Best Quality on Ebay Grade A | |
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US $259.00 | 1h 9m |
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Chevrolet Corvette Convertible 2003 Chevrolet Corvette Convertible LOW MILES | |
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US $24,999.00 | 2h 33m |
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50Bayonet Downlight Ceiling Studio 110v Led LightW220 | |
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US $348.00 | 8h 31m |
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10Bayonet Downlight Ceiling Studio 110v Led LightW220 | |
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US $148.00 | 9h 21m |
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10 4W GU10 110v Bulb Light White 45° CREE LED XLamp4W | |
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US $138.00 | 10h 10m |
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100GU10 Blue 18 Led Restaurants Light Bulb DC 12VGB18 | |
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US $378.00 | 10h 57m |
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100GU10 Blue LED HOME Restaurants Light Bulb 12VGB18 | |
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US $378.00 | 11h 1m |
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Big Island Flower TIKI LED Solar Light H 36xD 85 | |
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US $119.00 | 12h 36m |
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New 8 Reflector Telescope With Dual Motor Drive Tripod | |
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US $499.99 | 18h 15m |
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150W High Power LED Landscape Flood Spot Light Lighting | |
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US $747.00 | 18h 35m |
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BLUE LIGHT THERAPY ORAL IRRADIATION KILL BACTERIA COLD | |
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US $285.00 | 21h 11m |
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Fire Magic Echelon 48 inch Cabinet Gas Grill E1060s | |
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US $12,323.30 | 23h 25m |
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Jen TIKI With LED Solar Spot Light H 42 x D 10 | |
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US $149.00 | 23h 42m |
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New 8 Reflector Telescope with Twin Motor Drive Tripod | |
0 Bid | US $499.99 | 1d 5h 48m |
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40 x White LED Spot MR16 Light Bulb 110V AC E26 Base | |
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US $225.99 | 1d 7h 21m |
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10E27 4 Watt Bulb Light 45° CREE LED XLamp 12VE4W | |
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US $138.00 | 1d 7h 50m |
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1957 Chris Craft Custom Constellation | |
12 Bids | US $8,300.75 | 1d 8h 4m |
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10GU10 Base 3W White Led 110V 240V Home DownlightGW22 | |
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US $168.00 | 1d 9h 42m |
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10x MR16 3X1W 12V White LED Spot Down light BulbM12 | |
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US $158.00 | 1d 9h 48m |
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100 E27 Yellow 18 Led Studio Spot Light Bulb 220VY18 | |
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US $378.00 | 1d 10h 5m |
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103W E27 Wall White Studio Spot 110V AC Light BulbE3A | |
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US $158.00 | 1d 10h 10m |
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50 x 3W 12V Energy Saving White LED Spot Light Bulb94 | |
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US $708.00 | 1d 10h 15m |
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100 E27 Blue 18 Led Studio Spot Light Bulb 220V B18 | |
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US $378.00 | 1d 10h 20m |
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100MR16 12V Colorful Flash 18 Led Spot Light BulbC18 | |
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US $408.00 | 1d 10h 24m |
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103W E27 Wall White Studio Spot 110V AC Light BulbE3S | |
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US $158.00 | 1d 10h 47m |
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NEW AMAZON KINDLE DX GLOBAL WIRELESS | |
7 Bids | US $202.50 | 1d 16h 33m |
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24 Stainless Steel Plastic Hexagon 3 LED Solar Light | |
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US $210.00 | 1d 16h 42m |
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24 Copper Stainless Steel Plastic Hexagon 3 LED Solar L | |
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US $204.00 | 1d 16h 51m |
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12 Stainless Steel Hexagon 3 LED Solar Light | |
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US $110.00 | 1d 16h 53m |
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6 x Ultra Bright 6 LED Solar Spot Light Garden Patio | |
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US $110.95 | 1d 23h 6m |
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40 Height Huge Outdoor Wall Light Lighting OT0032B WU | |
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US $142.90 | 2d 2h 5m |
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Rugged Color Mil Spec Chartplotter Tablet PC WIFI GPS | |
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US $349.00 | 2d 3h 49m |
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103W MR16 LED 12V Home Studio Bar White DownlightMW12 | |
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US $168.00 | 2d 4h 26m |
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100MR16 GU53 Purple Violet 18 Led 12V Light BulbMP18 | |
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US $378.00 | 2d 8h |
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NEW NEW NEW HUZAR 28 SAILING YACHT | |
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US $79,900.00 | 2d 8h 55m |
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10 3W 3 Watts 110V 240V Garden Home Led Downlight 127 | |
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US $168.00 | 2d 10h 7m |
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10 3X1W MR16 Halogen Warm White LED Downlight Bulb157 | |
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US $158.00 | 2d 10h 9m |
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Lot of 100x 78 LED GU10 WarmWhite Spot Light Bulbs DHL | |
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US $759.99 | 2d 12h 59m |
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10 X MR16 LED DOWNLIGHT Spotlight 12V 3W 25W Halogen | |
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US $102.40 | 2d 13h 55m |
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12x78 LED GU10 Warm White Spot Light Bulb 2Pin 220 240V | |
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US $102.40 | 2d 13h 55m |
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10 X MR16 LED DOWNLIGHT Spotlight 12V 4W 40W Halogen | |
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US $110.96 | 2d 13h 55m |
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Lot 10pcs GU10 LED Warm White Spotlight Downlight 3W | |
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US $102.40 | 2d 13h 55m |
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10x E27 LED DOWNLIGHT Spotlight Bulb 31W 30W Halogen | |
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US $102.40 | 2d 13h 56m |
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Lot 10pcs GU10 LED Cool White Spotlight Downlight 3W | |
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US $102.40 | 2d 13h 56m |
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12x78 LED GU10 Cool White Spot Light Bulb 2Pin 220 240V | |
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US $102.40 | 2d 13h 56m |
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Orlando Disney World Vacation Home House Rental | |
US $129.00 | 2d 14h 35m |
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50GU10 4X1W LED Down Spot Light Warm White 45° 230V 4W | |
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US $668.00 | 2d 17h 52m |
Znamya 2 calculation?
The Russian Znamya 2 was a 20-meter wide (flat) mirror, launched in 1992. It was
designed to test the feasibility of illuminating parts of the Earth’s surface by reflecting
sunlight from orbiting mirrors. Znamya 2 was deployed (for a few hours only) near
the space station MIR, orbiting at an altitude of
∼ 390 km.
(a) Calculate what size spot on the Earths surface was illuminated by Znamya 2.
(b) Assuming the mirror was optimally positioned so that it was
∼ perpendicular to
light from the Sun, how much solar energy did it receive per second ?
The Sun is about 1/2 degree wide in the sky, so the cone of light cast by an infinitely small mirror would be 1/2 degree wide or 390km * Tan 0.5 degree = 3.4 kilometer wide spot on the ground. So the 20 meter wide mirror make a spot 3.4 km + 20 meters wide, or 3.42 km wide. The area would be about 9,186,331 square meters, or almost 30,000 times larger in area than the 314 square meters area of the 20 meter mirror (assuming it is round). So the sunlight would be 30,000 times less intense than direct sunlight.
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Solar Sun Tracker PVCOOL 4m2 BP Kyocera Sharp Suntech | |
|
US $446.49 | 44m |
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Solar Tracking System ST 6 DIY kit suit for any panels | |
|
US $536.69 | 44m |
|
MP3 KIDS RIDE ON R C CAR REMOTE CONTROL POWER WHEELS RC | |
|
US $184.95 | 49m |
|
100w JL Mono Solar Panel Best Quality on Ebay Grade A | |
|
US $259.00 | 1h 9m |
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Chevrolet Corvette Convertible 2003 Chevrolet Corvette Convertible LOW MILES | |
|
US $24,999.00 | 2h 33m |
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50Bayonet Downlight Ceiling Studio 110v Led LightW220 | |
|
US $348.00 | 8h 31m |
|
10Bayonet Downlight Ceiling Studio 110v Led LightW220 | |
|
US $148.00 | 9h 21m |
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10 4W GU10 110v Bulb Light White 45° CREE LED XLamp4W | |
|
US $138.00 | 10h 10m |
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100GU10 Blue 18 Led Restaurants Light Bulb DC 12VGB18 | |
|
US $378.00 | 10h 57m |
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100GU10 Blue LED HOME Restaurants Light Bulb 12VGB18 | |
|
US $378.00 | 11h 1m |
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Big Island Flower TIKI LED Solar Light H 36xD 85 | |
|
US $119.00 | 12h 36m |
|
New 8 Reflector Telescope With Dual Motor Drive Tripod | |
|
US $499.99 | 18h 15m |
|
150W High Power LED Landscape Flood Spot Light Lighting | |
|
US $747.00 | 18h 35m |
|
BLUE LIGHT THERAPY ORAL IRRADIATION KILL BACTERIA COLD | |
|
US $285.00 | 21h 11m |
|
Fire Magic Echelon 48 inch Cabinet Gas Grill E1060s | |
|
US $12,323.30 | 23h 25m |
|
Jen TIKI With LED Solar Spot Light H 42 x D 10 | |
|
US $149.00 | 23h 42m |
|
New 8 Reflector Telescope with Twin Motor Drive Tripod | |
0 Bid | US $499.99 | 1d 5h 48m |
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40 x White LED Spot MR16 Light Bulb 110V AC E26 Base | |
|
US $225.99 | 1d 7h 21m |
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10E27 4 Watt Bulb Light 45° CREE LED XLamp 12VE4W | |
|
US $138.00 | 1d 7h 50m |
|
1957 Chris Craft Custom Constellation | |
12 Bids | US $8,300.75 | 1d 8h 4m |
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10GU10 Base 3W White Led 110V 240V Home DownlightGW22 | |
|
US $168.00 | 1d 9h 42m |
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10x MR16 3X1W 12V White LED Spot Down light BulbM12 | |
|
US $158.00 | 1d 9h 48m |
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100 E27 Yellow 18 Led Studio Spot Light Bulb 220VY18 | |
|
US $378.00 | 1d 10h 5m |
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103W E27 Wall White Studio Spot 110V AC Light BulbE3A | |
|
US $158.00 | 1d 10h 10m |
|
50 x 3W 12V Energy Saving White LED Spot Light Bulb94 | |
|
US $708.00 | 1d 10h 15m |
|
100 E27 Blue 18 Led Studio Spot Light Bulb 220V B18 | |
|
US $378.00 | 1d 10h 20m |
|
100MR16 12V Colorful Flash 18 Led Spot Light BulbC18 | |
|
US $408.00 | 1d 10h 24m |
|
103W E27 Wall White Studio Spot 110V AC Light BulbE3S | |
|
US $158.00 | 1d 10h 47m |
|
NEW AMAZON KINDLE DX GLOBAL WIRELESS | |
7 Bids | US $202.50 | 1d 16h 33m |
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24 Stainless Steel Plastic Hexagon 3 LED Solar Light | |
|
US $210.00 | 1d 16h 42m |
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24 Copper Stainless Steel Plastic Hexagon 3 LED Solar L | |
|
US $204.00 | 1d 16h 51m |
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12 Stainless Steel Hexagon 3 LED Solar Light | |
|
US $110.00 | 1d 16h 53m |
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6 x Ultra Bright 6 LED Solar Spot Light Garden Patio | |
|
US $110.95 | 1d 23h 6m |
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40 Height Huge Outdoor Wall Light Lighting OT0032B WU | |
|
US $142.90 | 2d 2h 5m |
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Rugged Color Mil Spec Chartplotter Tablet PC WIFI GPS | |
|
US $349.00 | 2d 3h 49m |
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103W MR16 LED 12V Home Studio Bar White DownlightMW12 | |
|
US $168.00 | 2d 4h 26m |
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100MR16 GU53 Purple Violet 18 Led 12V Light BulbMP18 | |
|
US $378.00 | 2d 8h |
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MAXSA Innovations 40225 Solar-Powered Motion-Activated 80 LED Security Floodlight List Price: $129.95 Sale Price: Too low to display Used From: $70.00 Average Rating:   |
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Solar - powered easy and BRIGHT effective! 80 - LED Motion - activated Solar Floodlight, PRICED LESS! Utility and security light for your garage, driveway, walkway or shed... convenient, easy-install, no wiring hassles or energy costs, even! It's solar powered, automatic and brilliant! Swivel-head Light with 80 LEDs and a silver reflector for big, bright coverage... |
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Paradise GL23836BK2 Plastic Solar Spot Light, 2-Pack, Black Sale Price: $69.99 Average Rating:  |
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Strathwood Solar Garden Path Spot Lights, Black, Set of 2 List Price: $69.99 Sale Price: $45.91 Average Rating:  |
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Strathwood Spot Lights illuminate garden or landscaping features beautifully. Made of black cast iron for strength and durability, each light is weather and element-proof. The black finish lends itself to a variety of outdoor settings... |
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High Power 160 Lumen Mr16 Gu5.3 Base Single LED 30 Deg. Spot Light 12v Bulb Warm White, 1204WW Sale Price: $12.00 |
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MR16 LED bulbs are now available in 3 Watt light output with an estimated lifespan for the LED driver of 100,000 hours! This LED lighting unit is probably the most powerful LED light source available today in a MR16 halogen type format... |
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Telescope Solar Filter by Seymour Solar for Meade ETX 125, 114EQ, and DS-2114 ATS Sale Price: $59.00 |
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This size filter will fit any telescope with an optical tube diameter of 143-149mm. It is made with a sturdy aluminum outer cell that houses an optical thin film aperture. The thin film is a .002" thick black polymer... |
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Telescope Solar Filter by Seymour Solar for Meade ETX 90 Sale Price: $49.00 |
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This size filter will fit any telescope with an optical tube diameter of 98-105mm. It is made with a sturdy aluminum outer cell that houses an optical thin film aperture. The thin film is a .002" thick black polymer... |