There's no picture of the handle, but from the description, it sounds like Bradley Walker's "Rock Crusher". He could probably provide dimensions of the grip area.
We had a few users of these in the club, but I noticed that they're not using them anymore. These handles are on the heavy side...not a big deal if you're flying a big model that pulls hard, but not so good when your model is small and/or line tension is light. Every little bit helps...or hurts.

Steve