This unique design of release bearing was used only on Verto clutch assemblies. Verto release bearings fit only on the correct plunger, DAM5353E.
Verto clutches are externally identified by a very short clutch arm, as shown in the photo. Order the arm DAM5355 separately if needed.
If you have the conventional early Mini (pre-Verto) clutch arrangement, use GRB0238 release bearing.