To be used with a water source of low pressure of 5 lbs. P.S.I., which is provided by a pressure-reducing valve or by gravity tanks placed less than 5’ above the drinkers. You can use a pressure-reducing valve or gravity-flowing water. Very sanitary. They use a spring for shut-off, which is very accurate. Water will only flow when the bird's beak is in the cup. These cup systems avoid the messy, wet spots you get with nipple drinkers. 
About 1/8 inch of the threads will be visible once screwed into the pipe bracket or the cage/wall bracket. Over-tightening will cause the bracket to split.
Each cup will require the Cage/Wall Mount or the PVC Pipe Fitting Connectors.