6 Guardian Pool Spa Filter Replaces Unicel C-4326 Spa Filter FC-2375 PLEATCO PRB25, 25 sq ft -Bottom Opening: 2 - 1/8" -Top Opening: 2 - 1/8" -Outside Diameter: 4 - 15/16" (Also replaces 5") -Length: 13 - 5/16" -REMAY Filter media