Designed to be a proper bottom bracket BB for installing SRAM GXP/ISIS2 cranks in either BB30, PF30, or Specializeds OSBB road frames. Our patent pending design keeps the cartridge bearings outboard of the frame right on SRAM spec for greater rigidity & free of frame/c-clip tolerance issues that other systems deal with. Simply press in the longer non-drive-cup, then the shorter drive cup threads into it. As the drive cup threads in, our trademark Collet system expands to a precise limit evenly dispersing pressure for a super tight fit. With both cups connected & our collet set exactly to spec, there is no chance the bearings can come out of alignment or wiggle/walk out of the frame. This design also uses a compressible o-ring on the non-drive side cup to compensate for frame shell width discrepancies. SPECIFICATIONS For SRAM GXP/ISIS2 cranks. Also for Oval Concepts 400/500/700series GXP cranks Forged & machined heat-treated 7075 T6 Aluminum Steel cartridge radial bearings 68mm Road version / 73mm MTB Version Available for BB30, PF30, & Specialized Road OSBB TECHNOLOGY Patent Pending Design Collet style non-drive cup expansion for wiggle-free press Compression/ Spacer O-Ring compensates for frame width discrepancies COMPATIBILITY Not for BBRight or BB386EVO frames 68mm cannot be used for MTB Cranks MTB Guides-ISCG05 Good, ST Mounted Good, ISCG03 Not Good