Carburettor connecting piece kit for Mikuni carburettors

Screw neck complete kit M42 for use with Mikuni TM-36, TM-40, TM-42 flat slide or VM-38 round slide carburettors (original on R100 models).
This bolt-on connecting piece kit fits all R80 and R100 models with M42 thread. The connecting pieces are required when using Mikuni TM-36, TM-40, TM-42 flat slide or VM-38 round slide carburettors on models with small intake manifolds (BMW R80, R80R models).
If the Mikuni carburettors are used on an R100, no conversion is required These models have the "large" screw neck and the "large" rubber sleeve already fitted. 

How can I check this: The screw neck must have an outer diameter (carburettor side) of 52mm. If the diameter is smaller, this screw socket kit is required.  

Price is per side, so 2 kits are needed.