Ball Valves – Minneapolis Pattern. A.Y. McDonald Ball Valve Curb Stops maintain their low turning torques and bubble-tight 300 PSIG water pressure rating due to the PTFE coated brass ball that is supported by two blow-out proof EPDM seals. The end piece joint is sealed with an EPDM o-ring and thread locker. McDonald Ball Curb Stops offer positive shut-off from either direction and are available with a wide variety of end connections or Minneapolis Curb Box Threads. A brass 2″ square operating head that is easily pinned to existing curb stops is available separately.