This kit features two heavy duty rubber isolation mounts, 2 hex nuts and 2 matching lock washers. The mounts are comprised of two independent studs with 5/16 threads that measure 1/2" in length. As these studs are independent of one another, they provide optimum vibration and noise reduction. The rubber center has a diameter of 1" and thickness (height) of 3/4".  

This kit also serves as a replacement for the Chamberlin ,Liftmaster 89LM & many Sears Craftsman openers.

12 Pc Kit contents:

4 - heavy duty rubber isolation mounts with 5/16 threads and 1/2" studs

4 - 5/16 hex nuts

4 - matching lock washers