External bottom bracket removal/installation wrench.
Fits all 16 notch external bottom brackets, including
Shimano Hollowtech II,
Campagnolo (Ultra-Torque and Power-Torque),
...And anything else using the same unique-enough-to-require-a-special-tool but no longer *that* unique/individual thankfully bottom bracket cups...
Steel, punched out of 4mm flat mild steel, plastic eight-splined thumb tool for the adjustment caps (...and it's bolted on... Because otherwise, you'll lose it...) - the internal diameter of the main tool throat is ~44mm.
Not as nice as a Park Tool one... Granted... But it's also not as $55+ as a Park Tool one either... :D If you're changing out bottom bracket bearings at home, this should do the trick until you eventually manage to lose it, or until they come up with another new style of putting bearings into bikes...