I picked up one of these along with the latest addition of TGM (7th) from thegolfingmachine.com. It didn't come with any instructions beyond the site's description that it fit "against the AFT side of the shaft".
I'm assuming the #3 pressure point is 'wedged' between the #3 Pressure Point Trainer and the grip, providing added resistance and thereby added feel of a maintained #3 pressure point?
I realize this may be a stupid question, but in absence of any definitive info on how to use it, I figure better safe than sorry.