Mixture screw for the Weber DCOM carburetor.
This is the version that uses an o-ring rather than a spring to lock its setting.
Required quantity per carburettor: 2
This is item number 57 in the drawing.
Weber Part Number: 64750.058
Dellorto, Weber and Solex Carburettors Spare Parts Jets Chokes Emulsion Tubes Service Kits