Available in many sizes, styles and hardness from Element14 (formerly Farnell) for their usual extortionist pricing. I'm sure they'd be available from other sources with better prices.

http://www.farnell.com/datasheets/1286912.pdf

Interesting it was the Gator soft mount for the Hanno I first encountered these, years later when the internet came along I realised they aren't designed for use in tension, only compression and shear?? Never had (or heard) of any problems with them event though everyone in the pattern game uses them in tension (mostly)...