A.Y. McDonald Ball Style Corporation Stops come standard with a 360 deg operating head and are designed for low turning torques and operating pressures up to 300 psi. The brass ball is coated with PTFE and supported by two blow-out proof EPDM seals. The end piece that holds the ball in the body is sealed with an EPDM O-ring and thread locker. A.Y. McDonald ball valves have no metal-to-metal contact between the ball and the body to cause higher turning torques and increased wear on the ball. The leak proof feature at 300 psi rating makes these valves a better choice than a plug valve when test or operating pressures exceed 80 psi.