The FSA BB30 MTB Bottom Bracket is 2 bearings that are directly pressed into the frame & seated against a cir-clips that are installed into machined grooves in the bottom bracket shell. To have a BB30 compatible shell on your frame the inner diameter needs to measure 42mm & have no threads on the inside. This is a replacement for the standard FSA BB30 cartridge bearings that make up the bottom bracket. It comes with bearing covers & cir-clips. This BB will work with FSA SLK, Afterburner, V-Drive, Comet & Gravity BB30 cranks.