1/2 Inch Full Port Ball Valve Pex With Waste Has A Blowout Proof Stem And A Bleeder. The Blowout Proff Stem Ensures That Even If The Pressure Is Raised, The Stem Will Not Blow. The Bleeder Is Used To Drain Excess Water To Avoid Overflow. It Is Made Of Quality Materials Including A Forged Brass Body And A Chrome Plated Finish.