The Pentair Lid O-Ring #2-357 (357255Z) is the OEM replacement strainer lid seal for Pentair SuperFlo, SuperMax, and OptiFlo pump families, including variable speed models. This O-ring seats between the strainer pot body and the clear lid, creating the airtight, watertight seal that keeps the pump primed and prevents air from entering the suction side of the system. When this seal degrades — through UV exposure, chemical wear, or compression set — the pump may lose prime, run dry, or develop an audible air leak at the lid. Replacing it restores a proper seal and protects pump performance. Match the part number stamped or molded on your existing O-ring before ordering. Specifications Pentair Part Number 357255Z Part Name O-Ring, Lid #2-357 Quantity Included 1 (Each) Fits Into Brand Equipment Line Model / Part Number Notes Pentair SuperFlo VS Variable Speed Pump — SuperFlo VS/VST Series SUPERFLO VS Pentair SuperFlo VST Variable Speed Pump — SuperFlo VS/VST Series SUPERFLO VST Pentair SuperFlo VS/VST Variable Speed Pump — SuperFlo Series SUPERFLO VS/VST Pentair SuperFlo VS/VST Variable Speed Pump — SuperFlo Series SUPERFLO-VS-VST Pentair SuperFlo 3/4 HP Single Speed Motor — SuperFlo Series 354803S SuperFlo Pump lid O-ring No. 2-357 Pentair SuperFlo 1 HP Single Speed Motor — SuperFlo Series 354821S SuperFlo Pump lid O-ring No. 2-357 Pentair SuperFlo 1-1/2 HP Single Speed Motor — SuperFlo Series 354823S SuperFlo Pump lid O-ring No. 2-357 Pentair SuperFlo 2 HP Single Speed Motor — SuperFlo Series 354815S SuperFlo Pump lid O-ring No. 2-357 Pentair SuperMax VS Variable Speed Pump — SuperMax Series SUPERMAX VS Pentair SuperMax VS Variable Speed Pump — SuperMax Series SUPERMAX-VS Pentair SuperMax — SuperMax Series 348191 O-Ring, Lid #2-357 Pentair SuperMax Motor 3/4HP — SuperMax Series 354804S O-Ring, Lid #2-357 — SuperMax Pump part Pentair SuperMax Motor 1HP — SuperMax Series 354822S O-Ring, Lid #2-357 — SuperMax Pump part Pentair SuperMax Motor 1-1/2HP — SuperMax Series 354824S O-Ring, Lid #2-357 — SuperMax Pump part Pentair SuperMax Motor 2HP — SuperMax Series 354816S O-Ring, Lid #2-357 — SuperMax Pump part Pentair SuperMax Motor 1HP SQFL — SuperMax Series 355021S O-Ring, Lid #2-357 — SuperMax Pump part Pentair SuperMax Motor 1-1/2HP SQFL — SuperMax Series 355023S O-Ring, Lid #2-357 — SuperMax Pump part Pentair SuperMax Motor 2-1/2HP SQFL — SuperMax Series 355027S O-Ring, Lid #2-357 — SuperMax Pump part Pentair Efficient SuperMax Motor 1.5HP SQFL — SuperMax Series 355011S O-Ring, Lid #2-357 — SuperMax Pump part Pentair Efficient SuperMax Motor 2HP SQFL — SuperMax Series 355013S O-Ring, Lid #2-357 — SuperMax Pump part Pentair OptiFlo Pump — OptiFlo Series OPTIFLO Compatibility is based on Pentair parts documentation and available OEM records. This is not an exhaustive list. For certainty, verify the part number in your equipment's manual or on the original part itself before ordering. Pro Tip Any time the strainer lid is removed for basket cleaning or pump service, lightly lubricate this O-ring with a silicone-based pool lubricant before reinstalling. Petroleum-based lubricants will degrade the O-ring over time. If you are opening the pump for a shaft seal or impeller replacement, replace this lid O-ring at the same time — it is an inexpensive step that eliminates a common source of post-service air leaks.
