This is the white plastic sleeve that sits down inside your Dellorto PHF clamp type carb, between carb body and intake manifold.
This sleeve measures 42mm x 45mm x 25mm tall.
Yes this is not a cheap item - we had to get a machine shop to make these for us as Dellorto won't do it.
NOTE: There is another slightly different sleeve that fit to SOME carb bodies where there is a thick weirdly shaped rubber ring present below it - found on CAGIVA models. This will NOT fit, as the OD is different. We have those sleeves which are Dellorto part # 11715 (click HERE) and, we have the carb rebuild kits which contain that rubber ring which are Dellorto part # 52557.77 (click HERE)