SMAKN 12V/24V 20A 100W PWM Solar Battery Charge Controller Waterproof IP68 IP68 waterproof level and aluminum outer shell is able to effectively prevent various kinds of corrosion. Automatic identification of 12V / 24V system voltage. LED digital display and waterproof key-operated operations, which makes use simple and convenient. Various kinds of status indication. Protection againse over-charge, over discharge and overload, protection against electronic shortcircuit and reverse connection.