About This 23% High Conversion Efficiency - Solar car battery maintainer with monocrystalline solar cells, monocrystalline cells peak at 23% efficiency, and the persuasive power generation rate be higher than polycrystalline amorphous in the same area. Reverse Protection, Battery Maintenance - It has a built-in blocking diode to prevent reverse charging, and battery reverses discharging. It not only keep the battery from drain dead but also extends its usage life. Durable and Waterproof - It uses ultra-clear, durable, low iron tempered glass, which has a robust light transmission and can resist hail, rain, and snow, and is easy to clean. Windproof and waterproof, but it can't be immersed in water. 12V Charger & Maintainer - Trickle charger & maintainer, can charge all kinds of 12V batteries. Suitable for the vehicles in outdoor work, travel, or camping training. Besides, it is ideal for daily maintenance of the battery in automobiles, motorcycles, ships, agricultural vehicles, snowmobiles, beach cars, and trucks. Overview Brand : M MEGSUN Material : Monocrystalline Silicon Item Weight : 0.63 Ounces Efficiency : Ultra Efficiency Maximum Voltage : 12 Volts