Guardian Filtration Products New GAURDIAN Antimicrobial Pool/SPA Filter (2) Pack FITS: C-5374RA,C-5374 UNICEL 5374 FC-2971,FC-2971M PLBS75, PLBS75-M Cal SPAS FC2971, MICROBAN 14 3/4'' LENGTH 5 5/16'' DIAMETER ANTIMICROBIAL ANTIBACTERIAL CAL SPA