Quoted from o-din:I wouldn't be surprised if PBR and Marco are using the same ones now. I only found out about the high qulity Marco has now as they are one of the best sources for some of the newer games I've gone thru, and got some when I ordered from them. Then I bought a bunch. The ones I got from PBR a few years ago were very good too but had some color variations and some seemed old stock. But they worked.
I'm pretty sure that PBR gets their rubbers from Happ