4 pack FIT:Pool/Spa WATKINS HOT SPRING C6430 UNICEL C-6430 PLEATCO PWK30 FC-3915 Outside Diameter: 5 - 7/8" (5 7/8") Length: 10 - 1/2" (10 1/2") Top Opening: 1 - 15/16" (1 15/16") Bottom Opening: 1 - 15/16" (1 15/16") Media Weight - 3 oz. SQ FT Media - 30' Unicel - C-6430 (C6430) Filbur - FC-3915 (FC3915) Pleatco - PWK-30 (PWK30)