4A508A2 (Apollo-Conbraco) | 2 Inch | 4A PVB Bronze Pressure Vacuum Breaker With Ball Valves | Npt Threaded Test Cocks (2 x Fnpt)The Apollo Model PVB4A And PVBLF4A Pressure Vacuum Breaker A Series Prevents Contamination of The Potable Water Supply Due to Back Siphonage. A Standard Integral Freeze Protection Relief Valve Serves to Reduce The Possibility of Damage Due to Intermittent Freezing Conditions. The Modular Check Valve Cartridge Provides a Captured Spring, a Replaceable Seat, And a Reversible Silicone Seat Disc. This Assembly Features Ball Valve Shutoffs With Stainless