Well, I ordered the 50mm size and received it the other day. It's way too small for the 480cc FX tank! I even tried it on the 300cc Best Fittings tank I have for my Dream-Tac Compact and can't get it on it either! The Best Fittings tank has a glossy finish, and even using soapy water, I can't get it on! I thought about putting it out in the sun to soften it a bit and maybe let it stretch some, but if it's truly shrink wrap, then I fear putting it in the sun to warm will have the opposite effect! So, at this point, it seems it was a waste of money. Any suggestions on how to get it on a CF Bottle?