WARNING: This page is about a different car, the 2018 BMW 340i, 2017 BMW 340i, and 2016 BMW 340i. However, it is still accessible from the selected car via links, so may be relevant.
Use
(Valve spring cage) For removing and lining the valves.
Courtesy of BMW OF NORTH AMERICA, INC.
Use
(Valve spring cage) For removing and lining the valves.