[Shoebox]

Looking over a couple canisters that I have, I noticed that some had a "spacer" at the bottom of the tube and a spring/washer on the cover, both are not removable. Looking at an NOS canister (got from Barnfind) and it has none of the above. I see that the bumps formed in the bottom of the nos canister are more pronounced, perhaps eliminating need for the spacer? A Wix filter fits in properly. Is this simply a production change thing? Just curious. Thanks