2 pk Hayward Chlorinator 100 Inline and Offline Series Lid O-ring CLX110K Hayward Chlorinator 100 Inline and Offline Series Lid O-ring from Professor Foam CLX110K CL100 you get 2 lid orings These are standard pool industry buna 70 o rings, not Viton fits: Models CL100, CL110, CL110BR