The fsa bb30 mtb bottom bracket is 2 bearings that are directly pressed into the frame and 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 and 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 and cir clips this bb will work with fsa slk afterburner v