This is a genuine OEM part, not a pattern / aftermarket item. It will fit:
Two Stroke: M3.5B2, M4C and M5B.
Four Stroke: All 2.5HP, 3.5HP, 4HP, 5HP and 6HP models.
If you have any doubts as to whether this will fit your outboard, please email the model and serial number, and I will be able to inform you of the correct one.