Use a male adapter when connecting to galvanized, CPVC, or brass. On Flair-It 06000 Series and 16000 Series you can use both pipe dope and Teflon tape. On Flair-It 07000 Series and 17000 Flair-It Plus Fittings you may only use Teflon Tape (No Pipe Dopes or Liquid Teflons). When connecting to metal with a plastic fitting always use a male adapter. Do not use a plastic female adapter when connecting to metal male pipe threads.