For : MerCruiser I,R,MR,Alpha One,TR,TRS & all O/Bs with 3/8-16 non-magnetic gear lube fill or vent screws
Thread Size: 3/8" or 9.5mm - 16
The Sierra 18-2244 Drain Plug is interchangeable with the following: Chrysler F40109, GLM 22420, Mallory 9-72650, Mercury/Mercruiser 816610A2, 816610A1, 10-28634A1, 10-28634, 10-79953, 10-79953A2, 10-79953Q2, 10-79953Q04. Each Sierra product meets or exceeds the original equipment part it replaces.