Quick connect fittings end stop size 1/2 inches Works with copper, CPVC, Pex, LPDE, MPDE, HDPE and polybutylene tubing in hot and cold water applications. Incorporates stainless steel gripping teeth in the collets, allowing the connectors to interconnect with multiple materials without special tools or tube inserts. Exclusive O-ring guide insures zero-leak connections. Tube orientation can be changed by a simple twist, reducing the amount of tubing required to plumb a water system. Reusable, approved for use behind walls and underground.