The Pentair ABS Backwash Slide Valve O-Ring Rebuild Kit - Pentair 273109 is a replacement O-ring. This pool O-ring is made out of a strong rubber that is designed to hold up under high pressure and extreme temperatures. The Pentair 273109 is an O-ring rebuild kit that is designed to be an effective replacement for worn out or broken parts. This Pentair O-ring is designed for reliable performance and will work at a high level for the customer. - SKU: BAYST3787