2-Pack Chlorinator Lid Replacement O-Ring For Pentair Rainbow Models 300/320 R172009 O-283 2 Pack Quality Replacement Parts by Professor FoamFits the Model numbers: 300 and 320 Fits Models: 300 and 320 chlorinators order will arrive in sealed poly bag from Professor Foam This O Ring is made from Buna-N material Silicone lube with PTFE is available for an additional charge.