Bought a dealer out and these were in a box. Beck only was a aftermarket parts distributor for cars and motorcycle parts. I determined these are for a Honda because I used to deal with the company back then and I assume it's a single cylinder Honda because one cap is for the intake and one cap is for the exhaust. I don't know exactly what size Honda or what year or model. I'm just going by recollection. You can see from the pictures there's some oxidation on these parts from sitting for decades.