This Drive Dog screws onto the standard European & Asian 4mm threaded boat shafts. This allows you to use standard USA 3/16' drive dog type boat props on the 4mm European threaded shafts when used with a sleeve adapter or use of 4mm prop that has a drive dog slot. Includes (1) 4mm threaded drive dog. Requires: Prop nut4mm to 3/16 sleeve pn# ose-83400-4316