Harley Davidson Replacement O-rings for part #11105 for Oil, Transmission and Primary “Drain Plugs” They are used on Twin Cam engine oil, transmission and primary drain plugs on most late model Harley’s. They resist chemicals and oil better than the cheaper Buna-N O-rings being sold. The O-rings are stored, packaged, and shipped in a sealed pouch to keep O-ring's clean and from drying out. Change your oil every 5000 miles as recommended by the factory. You can buy cheaper O-rings, and change your oil every 3000 miles which requires more work, and more money on oil. Check your manual to be sure H-D replacement part #11105 is what you use.