Seaplane Outfitters plugs.
These plugs are installed as plugs or check valve. They do not have to be removed. Simply place your bilge pump over the plug and pump. Each stroke of the pump opens the Seaplane Outfitter valve to allow water out. The valve is normally closed to prevent water from entering the float compartment‘s.
This list of manufactures and their model floats will give you information on the amount of compartments for each model floats. Commonly each water tight compartment requires one Pump Out Plug.