Some of the Advantages to the Brown Weight Valve include:

Built using durable materials and construction – providing years of life!
Machined HDPE (high density polyethyline) housing and weight
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)

float valves

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 uses a spring loaded, naturally closed water valve.  When the water level goes down the weight on the arm pushes the valve open.  The weight is made of a durable plastic that is slightly less dense than water.  As the trough fills the weight floats up with the water level until the trough is full, allowing the valve to close.