52- Dude, I've tried that site and get so confused when I go there! I know you have a KM3 now - can you tell me which Oring this one is? I'd be eternally grateful, as it's the one that wears out most often, and I can't seem to find it on the oring sites. The one you showed is listed on the site as a 5 (is the number ID or OD?), but id is 5 and od is 7, and CS is only 1, so it doesn't compute with me. I don't know whether I'm looking for a 5 or 7? And I can't even find a 7 in the same ring you show.... I'm just not smart enough to shop for o-rings, I guess!