Plug Screw for Rotax Max Evo carburetors. This is the OEM screw that 'plugs' the bottom of the float bowl area on Dellorto VHSB carburetors.
Typically, this screw fits a 17mm open-end wrench or socket, and allows for rapid removal and change of the main jet in the carburetor upon removal.
Note that Rotax also allows a 'thumb' type plug to be used in the carburetor, which can make adjustment of the carburetor a little easier with less tools needed.
This plug also comes with a compressible O-ring gasket, that once tightened ensures a proper seal of fluid and air inside the carburetor to prevent leaks at the bottom of the bowl.