This solar panel is using the most expensive and highest performance solar cells so the price could be slightly higher than the really cheap Amorphous type on Ebay. There are three types of Solar Cells on the market. This solar charger is using the best Mono-Crystalline Solar Cells:
Mono-Crystalline - 25 plus years service life and up to 20% efficiency. This is the same type use in solar car racing. This type of solar cells is now in worldwide shortage because only a few companies can manufacture this type solar cell. The raw material which is a special kind of silicon sand ore is also in great shortage. It is in black color circular or semi-circular silicon wafer form in appearance.
Product Dimensions: 11.5 x 9.5 x 1 inches, Weight 2.2 lbs
Any 12V rechargeable battery, you may need to use charging controller to have auto shutoff to prevent overcharge. However, you can unplug manually when it is fully charge.