For 1976 & later Mercury/Mariner 2-cyl, 30-40 Hp | 3-cyl, 40-60 Hp | 4-cyl, 75-175 Hp | 6-cyl, 200-400 Hp | V6, 115-300 Hp outboards.
ID: 2.1875″ | OD: 2.375″ | W: 0.09375″

also crosses with:
Sierra: 18-7176
GLM: 81395, 81390
Mallory: 9-76554