it's all the parts supplied with the piston, if you put one clip in then slide the pin in you can see that it's a hair long and covering up the edge of the clip groove not letting it seat all the way, it's more common than you think and I see it a lot with snowmobile pistons. I have one more wiseco piston in stock right now so I'll pull it out of the box and check that one. will measure it and repost. haven't called wiseco, most of the time manufactures don't care about stuff like this when told, you get "yes we'll take a note of that" or "the mechanic should have noticed that on installation".