This thin metal washer sits on the underside of the front upper strut mount. It fits against the bearing and seals in the bearing grease and keeps dirt, dust, and debris from getting in. It's essential to ensuring the longevity of your strut bearing. Many times they can be re-used but since it's exposed on the bottom of the mount it often gets corrosion and should be replaced whenever the strut and mount are apart.
BMW Fitments:
1 Series
E82 / E88 (08-13) > 128i
E82 / E88 (08-13) > 135i N54 (08-10)
3 Series
E21 (75-83) > 320i
E21 (75-83) > 323i
3 Series
E30 (84-91) > 318i
E30 (84-91) > 318is
E30 (84-91) > 325e
E30 (84-91) > 325es
E30 (84-91) > 325i
E30 (84-91) > 325is
E30 (84-91) > 325ix
E30 (84-91) > M3
3 Series
E36 (92-99) > 318i M42
E36 (92-99) > 318i M44
E36 (92-99) > 318ic M42
E36 (92-99) > 318ic M44
E36 (92-99) > 318is M42
E36 (92-99) > 318is M44
E36 (92-99) > 323ic
E36 (92-99) > 323is
E36 (92-99) > 325i
E36 (92-99) > 325ic
E36 (92-99) > 325is
E36 (92-99) > 328i
E36 (92-99) > 328is
E36 (92-99) > M3 (1995)
E36 (92-99) > M3 (96-99)
3 Series
E46 (99-05) > 320i
E46 (99-05) > 323Ci
E46 (99-05) > 323i
E46 (99-05) > 325Ci
E46 (99-05) > 325i
E46 (99-05) > 325xi
E46 (99-05) > 328Ci
E46 (99-05) > 328i
E46 (99-05) > 330Ci
E46 (99-05) > 330i
E46 (99-05) > 330xi
3 Series
E90 / E91 / E92 / E93 (06-13) > 323i
E90 / E91 / E92 / E93 (06-13) > 325i
E90 / E91 / E92 / E93 (06-13) > 325xi
E90 / E91 / E92 / E93 (06-13) > 328i
E90 / E91 / E92 / E93 (06-13) > 328xi
E90 / E91 / E92 / E93 (06-13) > 330i
E90 / E91 / E92 / E93 (06-13) > 330xi
E90 / E91 / E92 / E93 (06-13) > 335d
E90 / E91 / E92 / E93 (06-13) > 335i N54 (07-10)
E90 / E91 / E92 / E93 (06-13) > 335i N55 (11-13)
E90 / E91 / E92 / E93 (06-13) > 335is N54
E90 / E91 / E92 / E93 (06-13) > 335xi N54 (07-10)
E90 / E91 / E92 / E93 (06-13) > 335xi N55 (11-13)
5 Series
E28 (82-88) > 528e
E28 (82-88) > 533i
E28 (82-88) > 535i
E28 (82-88) > M5 (87-88)
5 Series
E34 (89-95) > 525i M20
E34 (89-95) > 525i M50
E34 (89-95) > 530i
E34 (89-95) > 535i
E34 (89-95) > 540i
E34 (89-95) > M5 (91-95)
5 Series
E39 (97-03) > 525i
E39 (97-03) > 528i 97-98
E39 (97-03) > 528i 99-00
E39 (97-03) > 530i
5 Series
E60 / E61 (04-10) > 525i M54 (2004-2005)
E60 / E61 (04-10) > 525i N52 (2006-2007)
E60 / E61 (04-10) > 525xi N52 (2006-2007)
E60 / E61 (04-10) > 528i
E60 / E61 (04-10) > 528xi
E60 / E61 (04-10) > 530i M54 (2004-2005)
E60 / E61 (04-10) > 530i N52 (2006-2007)
E60 / E61 (04-10) > 530xi N52 (2006-2007)
E60 / E61 (04-10) > 535i
E60 / E61 (04-10) > 535xi
E60 / E61 (04-10) > 545i
E60 / E61 (04-10) > 550i
6 Series
E24 (77-89) > 633CSi
E24 (77-89) > 635CSi
E24 (77-89) > M6
6 Series
E63 / E64 (04-10) > 645Ci
E63 / E64 (04-10) > 650i
X1 Series
E84 X1 (2013-2015) > X1 28i
E84 X1 (2013-2015) > X1 28i xDrive
E84 X1 (2013-2015) > X1 35i xDrive
X3 Series
E83 X3 (04-10) > X3 2.5i M54 (2004-2005)
E83 X3 (04-10) > X3 3.0i M54 (2004-2006)
E83 X3 (04-10) > X3 3.0si N52 (2007-2010)
Z Series
E36/7 / E36/8 Z3 (96-02) > Z3 1.9
E36/7 / E36/8 Z3 (96-02) > Z3 2.3
E36/7 / E36/8 Z3 (96-02) > Z3 2.5
E36/7 / E36/8 Z3 (96-02) > Z3 2.8 97-98
E36/7 / E36/8 Z3 (96-02) > Z3 2.8 99-00
E36/7 / E36/8 Z3 (96-02) > Z3 3.0
E36/7 / E36/8 Z3 (96-02) > Z3 M - S52
E36/7 / E36/8 Z3 (96-02) > Z3 M - S54
Z Series
E85 / E86 Z4 (03-08) > Z4 2.5i M54
E85 / E86 Z4 (03-08) > Z4 3.0i M54
E85 / E86 Z4 (03-08) > Z4 3.0i N52
E85 / E86 Z4 (03-08) > Z4 3.0si N52
Z Series
E89 Z4 (2009-2016) > Z4 sDrive28i
E89 Z4 (2009-2016) > Z4 sDrive30i
E89 Z4 (2009-2016) > Z4 sDrive35i
E89 Z4 (2009-2016) > Z4 sDrive35is