SMAKN&reg; DC-DC 6-24V to 5V 3A USB Charging Module Step-down Buck Power Supply Module Module Properties: Non-isolated High efficiency synchronous buck regulator, constant voltage module. Input voltage: DC 7-40V input DC voltage. (Prohibition AC input). Output voltage: DC 5V voltage output (perfect simulation computer USB output). Output Current: Rated 3A, enhance heat dissipation maximum 4A (adaptive output) with 5A insurance. Size:65.6mm * 20.8mm * 13mm(L*W*H).