The Pro BB Socket System is the ultimate solution to the ever-growing number of threaded bottom bracket standards flooding the market. This patent-pending, innovative, and efficient system adapts to both current and future bottom bracket tool needs with ease.At the core of the system is the Pro BB Socket Cup, designed to accept Pro BB Inserts via a secure magnetic connection, allowing for quick, effortless swapping with a satisfying click. As new bottom bracket standards emerge, additional inserts can be easily introduced, enabling mechanics to expand their toolkit affordably and efficiently.Completing the system is the optional Pro BB Socket Holder, which threads directly into the Cup. This crucial component prevents the socket from slipping off or pressing further onto the bottom bracket, effectively sandwiching it, and reducing the risk of injury or frame damage.Insert Shimano 16x44:- Fits 16-notch x 44 mm external bearing bottom bracket cups including Shimano® BB80, BB5700, XT BB70, BB51, and previous external bearing threaded cups. Also fits many external Threaded types for Campagnolo®, Chris King, FSA MegaExo, Hope, SRAM/Truvativ GXP, Race Face X-type, Surly, Wheels, and others. Also fits disc brake rotor lockrings with 16 external notches and Shimano® TL-FC24 and TL-FC25 adaptersFeatures:- Magnetic plug and play system replaces multiple BB sockets. Buy a single cup and pair with the inserts you need.- Pair the Pro BB Socket Cup with Pro BB Inserts, sold separately, to adapt to numerous types of threaded bottom brackets, disc lockrings, and more.- 7075 T6 aluminum socket is fully machined to precise tolerances for an exacting professional-level fit.- Features a 3/8´´ square drive for use with torque wrenches, a 24 mm external drive for use with Pedro´s Pro Socket Handle and pedal wrenches, and internal M12 thread for use with the Pro BB Socket holder.- Inserts are precision laser cut tool steel with optimized heat treatment for precise fit and superior tool life.