Top mount bearings that allow the strut to turn smoothly.
These bearings sit at the top of MacPherson struts and let the assembly rotate when steering. Wear can cause groaning, notchy steering or poor return to centre. Match bearing and mount style to the strut. Inspect the rubber mount at the same time. A good top bearing helps steering feel light and predictable.
Worn top bearings or mounts can cause noise and rough movement.
Yes. Many workshops replace mounts and bearings with new struts.
They mostly affect feel and noise, but play can influence how the strut sits.