Rather than try to explain, go to the website and read. I have tried several front motor mounts for my old FLHT. I preferred the Buell mount for the early FLs but, the softer rubber compound limited it's effective service life to about 2000k-3000k miles. Tried the early Glide Pro and it was good but not near as good as the later version that is now available. The big change was changing the size of the of the mounting bolt and fitment to the bushing as well as the different compound. It's a great piece.