I've always had a problem with the fit of the original o-ring gasket. They were so tight it was a pain to get them to stay in the groove while installing the derby cover. These fit perfect.. A little silicone grease holds it in place and you get a leak-proof seal the first time. Since they (HARLEY) quit making these and replaced with a paper gasket, which I couldn't get to work for me no matter what I did, finding these was a life saver. My old '94 FLHTC thanks you very much!