This is a stud kit to mount a Weber DCO/SP 48, 50 or 55 carburetor.
These shouldered studs give more clearance to enable thackery washers & nyloc nuts to be used.
The thread to to the manifold is 5/16 UNC thread.
The total length is some 40mm.
This set is supplied as a set of 4 studs, thackery washers & nyloc nuts, enough to mount 1 DCO/SP.