Quote Originally Posted by Heatnbeat View Post
What is this fixture used for?
Bench blocks have numerous uses. I use mine for driving pins into or out of small parts or small shafts. It can also be used as an anvil, although not for heavy duty use. I use the soft block anytime I have a delicate part, or a part where I don't want to damage the finish.

There is some more info here:

eBay Guides - BENCH BLOCKS Guide

http://rick.sparber.org/beb.pdf