This pneumatic test ball plug is designed for use in head pressure testing and back plug air testing. Item: Test Ball Plug Type: Pneumatic Nominal Size: 12" Min. Dia.: 10.50" Max. Diameter: 12.25" Max. Back Pressure: 40 ft. of Head Required Inflation Pressure: 25 psi Deflated Size: 13.83"L x 10.30"D Material: Natural Rubber For Use In: Head Pressure Testing And Back Plug Air Test