The Brown Weight Valves are spring loaded, naturally closed valves. When water is needed, the weight pulls down on the arm, providing leverage to open the valve. The solid weight is slightly lighter than water so when the water trough is full the weight floats, closing the valve. The Weight Valve is a recently invented choice to control water levels. For the past 100 years or so, float valves and their various configurations were the only choice. This product is NOT a float valve. These valves can be customized for various configurations (under water, small spaces, etc.). If you have any special needs, please contact garryatbrownweightvalve.com. Some of the Advantages to the Brown Weight Valve include:. Built using durable materials and construction – providing years of life!. Machined solid block HDPE (high density polyethylene) housing (vs injection molded light plastic housing for float valves) . Solid block HDPE (high density polyethylene) weight (vs hollow float valves susceptible to failure). A solid block of HDPE plastic will not fail!. All metal parts are made out of stainless steel (except one brass washer). Valve is relaxed when trough is full – if the valve breaks, water stays off (as opposed to the always-under-pressure float valves that flood when the valve breaks). The only pressure put on the piston is the weight on the arm. The weight is not attached to the valve (allowing it to rise with the water if the trough is filled above the set water level). Valves are built so that water cannot backflow Assembly is very simple. Item only consists of 3 main parts that are easily assembled with common tools included hardware and instructions.