The one I have only has one hole. It bothers me that it has no lock, and should it come loose, all hell would happen. Tried to drill a pilot hole and then drill a larger hole. Ruined two pilot drill trying to do this. Thought about putting a locking washer behind it, the thin metla kind, but think it might only flatten out and do no good. Only other choice is to tighten it excedingly tight and have locktight on the bolt. Stil no gaurantee that it won't come loose and slide. still hoping to find a used one. New eccentrics are around 25$. Seems like a lot of money for something so simmple looking. I have several for 390's but these have a larger hole for 7/16 bolt. Don't like that idea either. Thought about making spacer. Someone posted an my last request, taht the locking hole is not needed, but it still bothers me tonot have it. I don't want this coming off at high RPM, or even low RPM for that matter. Woould mean a complet overhaul either way if not caught soon enough, and my hearing is not that good.