Having a close fitting precise tool will prevent your bottom bracket being marred or chewed up from a loose fitting tool. Its durable for all day use or just now and then.
The most unique feature about this tool is the inner nub, that nub in the center of the tool is the same size as the crank spindle. What this does is give you a second point of contact that keeps the tool from camming off of the part. when trying to remove stubborn cups.
This dual sided socket is designed to work with the new Shimano DA-9000/XTR-BB93 bottom bracket as well 6800 Ultegra and 5800 105 11spd groups (BBR-60)