(5 Pack) CLX200K Hayward Pool Chlorinator Lid O-Ring for CL200/CL220 O-101 ( 5 Pack ) CLX200K Aftermarket Hayward Chlorinator Lid Replacement O-rings These o rings are Peroxide Cured EPDM - the highest resistance to chlorine you can get! Be sure you remove any dirt and debris from lid threads and use proper lube (not Petroleum) before use Professor Foam is including a FREE 1 G tube of Silicone PTFE lube Professor Foam started selling the EPDM after the negative reviews were left form other sellers who sold inferior o rings!