Venturi effect carburettor spacer block sand cast aluminum 20mm thick can be drilled, tapped or welded it is a premium grade of aluminum not brittle diecast.
The carb spacer is drilled 4mm so it can be used as a carburetor adapter or spacer. The AS0104 can be used with Aussiespeed AS0200 phenolic 2 barrel spacers to increase the height by a further 6mm or one on either side will give a total of 32mm and keep heat from getting to your carb.
This is drilled with pilot holes so it can be taped to 5/16 to accept studs or drilled out to fit over 5/16 carb studs.
You are buying the adapter only, it does not include gaskets or studs