Aqua Pure(TM) 63597-174C O-Ring Fits Aqua Pure(TM) AP11 and AP101 Series housings. Approximately 3.5"" x 3.75"". Replace after every third filter change. AirFilters.com This Aqua Pure(TM) 63597-174C O-Ring is designed for Aqua Pure(TM) AP11, AP26, AP51 and AP101 Series housings. It is approximately 3.5"" x 3.75"" and should be replaced after every third filter change. Purchase one today!
