It's that little rubber cushion that keeps your release off the arrow nock.

I switched for reasons similar to Greg's. At the time, I didn't have a bow press and I went through those buttons quickly and didn't want to have to take my bow to a shop to have it pressed.

Now that I do all of my own bow work, I've often thought of going back to shooting off the string, but I've grown comfortable using the Catfish Loop. I guess I just don't have a good reason to go back to attaching to the string.