This kit is designed to efficiently drive 1W / 3W Luxeon Leds from a power supply or a battery. Operates at 4-6VDC (Max. 20VDC). Efficiency is around 66% at 5V, 80% at 4V, 90% at 3V and 95% at 2.7V. This Luxeon Led driver is small, economical, simple and easy to assemble. Kit includes PCB and all on-board components.