Ball valves refer to unidirectional valves which are locked and unlocked via applying pressure on a ball fixed in a cup-shaped hole. 

The WA and WAS series differ in that the former does not include access fittings, but the latter does. The access fitting of a WAS Series valve can be found on the copper tube extension. 

Valves of both categories are made of brass and copper elements, and can conveniently be used without the user having to remove the seal cap. Further, these valves provide double-sealed protection without the use of O-rings.