SRAM's Crank Bearing Preload Adjuster For BB30/PF30 is used to adjust bottom bracket bearing preload on SRAM and Truvativ cranks in BB30 and Press Fit 30 shells. The adjuster threads onto the non-driveside crankarm and as you back it away from the arm, it closes the gap between the arm and bearing, increasing the preload and removing play. The setting is then held in place with a 2mm adjuster bolt. Always keep one on hand in the shop or on the road so you'll never be without your bike.