Pentair Challenger DiffuserReplacement diffuser for Pentair Challenger high pressure pumps (Pentair 355188Z), fitting 3 4 HP full rated through 1 1 2 HP up rated models including CHII NI 3 4F, CHII NI 1F, CHII NI 1A, and CHII NI 1 1 2A. It channels water off the impeller to build discharge pressure and restore flow when the original diffuser is cracked or worn. This OEM piece cross references 355188 and 35 5188; match it with the corresponding Challenger impeller for these HP