WARNING: This page is about a different car, the 2016 BMW Z4, 2015 BMW Z4, and 2014 BMW Z4. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
(Pressing-in tool) for pressing in the shielding caps on both sides in the fixed caliper shafts - brake piston diameter 54 - 57 mm/single-circuit brake system