Air Blower Check Valve 2" Type of product: Air Check Valve Specification: 2" S x 2" S Most common size reference: 2 inch Outer overall dimensions: Length:130mm Diameter:85mm Internal Diameter:49mm Commonly used with: 2 inch rigid pipe and 2 inch flexible rigid pipe. Spaform Spas and others, this is a fairly generic part.. Additional notes: To be used in an air loop to stop water getting back into the blower. 1/4lb of pressure