The Abbey Bike Tools DUB Bottom Bracket Drift is designed specifically to work with the Abbey Modular Bearing Press, and is used to install a SRAM DUB Press Fit bottom bracket into your bike frame. We already love the quality and functionality of Abbey's Modular Bearing Press, and this pair of drifts expands that capability to SRAM's relatively new DUB system. One of the main reasons SRAM created DUB is to improve bearing durability. The DUB 28. 99mm spindle and it's press fit bottom bracket use a special O-ring seal to achieve this goal, which in turn requires special bearing drifts to install the bottom bracket correctly. A normal drift with a square boss can easily tear this fragile O-ring, so Abbey incorporated a tapered boss that forces the small O-ring into its gland. That way your bottom bracket sees the durability it was designed to have all along.