Most single HIF44 installations use a 1/2" thick phenolic spacer between the carb and the inlet manifold. This normally is necessary for throttle arm clearance. However, we also supply this 6mm (1/4") phenolic spacer for custom installations where less thickness is required. Sold each.
Because You Asked:
Phenolic (noun): a usually thermosetting resin or plastic made by condensation of a phenol with an aldehyde and used especially for molding and insulating and in coatings and adhesives — called also phenolic resin.