Phil Wood offer two sizes of replacement outboard bottom bracket bearing dust covers. We have a standard dust cover which is good for Phil Wood OBB's as well as everything except newer Shimano, and a medium dust cover which is good for Phil Wood Philcentric cups as well as newer Shimano (Dura Ace, XTR) parts. The dust covers are made out of a high quality ABS plastic. For those using a SRAM/GXP you can also get one of our SRAM/GXP Adaptors for use with our outboard bottom bracket.