3/8" square hole can use for combining torque wrench & storing on the wall.
No need to dismantle crank arm, you can lock the BB adaptor directly.
11C1 16-Notch 44mm O.D. cups Hollowtech II
11C3 16-Notch 41mm O.D. cups BBR60
11C5 16-Notch 39mm O.D. cups BBX30
11C7 12-Notch 46mm O.D. cups BSA30
