O'Brien Replacement Boston Valve for O'Brien TowablesThe O'Brien replacement Boston Valve is a standard one way valve that will fit any O'Brien tube manufactured prior to 2016. This valve is for O'Brien towable tubes only and will not fit HO, Connelly, or Airhead tubes. When installing your new Boston Valve, make sure it is tight to prevent air from leaking.Thread diameter: 13/16"Note: This replacement valvewill notfit O'Brien tubes with Lightning Valves.California Residents:WARNINGCancer and Reproductive Harm -P65Warnings.ca.gov