I often get pin parts from Marco, but for some reason every time I order a rubber kit it seems the kit is always short one or two rings and/or includes one or two rings of a size that isn't needed. It's never a problem for me, but for somebody that doesn't have an assortment of extra's it would stink to come up short.
I'm not complaining about Marco, I've bought a lot there and been happy, but the ring kit thing annoys me a little. On the plus side, Marco usually includes a copy of the rubber layout diagram, which is handy if you don't have a manual.
Every rubber kit I've ever ordered from PB Resource has always been spot-on.
D