These insulatings seals are 3mm thick and this item is for an internal bore of 22mm (approx 0.875"), to fit flange fitting Amal carbs.(i.e. 2.00" between studs). These thick washers can seal as well as insulating the carb from excess engine heat..
Price per each.
Thicker than the paper type carb gasket we also sell (Item 0452/0453) - and less thick than the Tuffnol spacer rings we also offer, these 3mm thick gaskets/insulating seal's provide a gasket face for Amal flange fitting carbs (with 2.00" between stud centrres - which covers most Amal flange type carbs), but can also offer more heat insulation for the carburettor than the plain paper type washer. These are manufactured by a high quality specialist UK gasket manufacturer .
These are 22mm bore - which is a small bore (possibly smaller flange carbs fitted to many lightweight or 2 stroke models of the 1950's/60's), but this size also lends itself to being carefully trimmed with a sharp knife, to be opened out to whateve size your own carb inlet tract is - important if fitting to a racing motor with a specific size of Amal TT/RN/GP bore, that needs to be carefully blended. Obviously - if taking this route. . . . follow all normal safefy practices!!
I am supposing this type of gasket/inuslating seal would be useful when running motors that get hot, allowing the carb better insulation from that heat - and therefore a denser fuel mixture