Pentair Drain Plug O-Ring, Inner Diameter: 1/2 Inch, Thickness: 1/16 Inch, Buna-N 70 Shore, Packaging Quantity: 2/Pack, For Use With: Waterfall(R) Pumps, IntelliFlo(R) VF Pump, WhisperFlo(R) Pump, SuperFlo(R) Pumps, IntelliFlo(R) i1 Variable Speed Almon Colored Pumps, Sand Dollar(R) Filter Systems Manufactured Before 10/04, Triton(R) II Sand Filter Manufactured After 3-83 Thru 3-96, Challenger(R) High Pressure Pumps, Tagelus(R) Filter With THD and Clamp Valve, SuperMax High Pressure Pumps, Challenger(R) High Flow Pumps, OptiFlo(R) Pumps, IntelliFloXF(R) Pump, IntelliFlo(R) VS 3050 Pump, IntelliFlo(R) Variable Speed and IntelliFlo(R) VS SVRS Pump