Pentair 075207Z 1/4-Inch Valve Air Release Replacement SM and SMBW Pool and Spa D.E. Filter Valve air release replacement Fits Pentair SM & SMBW 4000 Series pool and spa sheet molded D.E. filters Also fits Pentair SM & SMBW 2000 Series pool and spa stainless steel D.E. filters Measures 1/4-inch