This is the rubber hanger used to support the rear muffler on all 1995-1999 M3s. It is also used on the 2001-2006 E46 M3 (there are three used on the E46 M3, so be sure to order enough for your needs).

This rubber exhaust hanger fits the following BMWs:
1995-1999 E36 M3 coupe, sedan & convertible
2001-2006 E46 M3 coupe & convertible