Auto-Drain provides completely automatic 12-volt push button operation of the valves that dump your RV's grey and black water holding tanks. It mounts onto the slide valve of a 3" or 1. 5" conventional waste valve and no plumbing modifications or difficult clamps are required. Works with Valterra and Bristol 3" and 1. 5" waste valve models (not included). Auto-Drain Valves are made of corrosion-resistant steel, aluminum and plastic. Before installing, your holding tanks should be emptied. There is an open or close cycle in less than 4 seconds for the 3" models. Included with the Auto-Drain Valve is a mounting bracket, rocker arm switch, switch box with light (indicates open or closed valve) and complete installation and operating instructions.