3312 rubber isolator used on the Burr King M25/45/85.  Isolators help keep the energy in the vibratory tub and isolate the vibration from the base.  Over time rubber will become hard and brittle or will loose it's elasticity causing performance issues with the vibratory machine.

The M25 and M45 use 4 while the M85 uses 8.

Suggested that when replacing one rubber isolator your replace all of them.