To prevent fuel vapors from the gas tank from leaking into the atmosphere the vapors are conveyed through a pipe system to an active carbon trap in the engine bay where they are absorbed. During engine operation hot air activates the carbon from which the gas vapors are extracted and conveyed to the intake manifolds. You can barely make out Svara lable. I believe Parker Hall has reproductions of this transfer. The canister is plated in yellow dichromate. This unit is standard equipment on USA Daytonas.