Pack of 5 high performance large hole vent plugs for Mercury / Quicksilver propellers.  Part # 889725047 (QTY 5)

Hole measures .470" or 12mm

Works for any Mercury or Quicksilver branded propeller with PVS vent holes approximately .69" (except for large tube Trophy)

From Quicksilver:

The Performance Vent System is an EXCLUSIVE Quicksilver innovation that allows you to "custom tune" the venting of your propeller blades - giving you the power to adjust your propeller to the way you boat.

The propeller is directly responsible for how your boat reacts in the water. PVS allows you to adjust for changes in load and environment simply by changing the propeller's vent plugs for optimum acceleration.