MIFAB® WHB Series (specify size) nesting type bellows operated water hammer arrestor with male N.P.T. connection. Bellows and body casing made of Type 304 stainless steel. WHB Series is certified to the PDI WH-201 Standard. Engineered to limit line system surge pressure up to 1500 P.S.I.G. shall be sized and located in accordance with manufacturer’s instructions.