This original BMW grommet seals the crankcase vent pipe to the bank 1 or bank 2 valve cover on 1996-2001 E38 750iL and 1996-1997 E31 850Ci.
This part is listed by BMW as BMW part number 11151702292 (11-15-1-702-292) and is described as Genuine BMW Boot/Grommet for Crankcase Vent Pipe on M73 V12 engine.
BMW Fitments:
7 Series
E38 (95-01) > 750iL
8 Series
E31 (91-97) > 850Ci