Shaft Size: 5/8 inch (0.625") Materials: Buna-N elastomers (rubber), ceramic stationary ring, molded plastic primary ring, and stainless- steel hardware/springs. Design Equivalence: Equivalent to a John Crane Type 6 / Type A rotary head. Operational Limits: Rated for pressures up to 75 PSI and maximum fluid temperatures of 225°F (107°C).