I recently treated myself to one of those, not sure whether or not it was the S&B one. Works very well indeed and a lot easier to get a tight hold, than struggling to tighten the brass nut enough, then retightening it every so often as I go.
I was very impressed, but I'm a newbie still at pen turning. I'd had problems a couple of times with the mandrel loosening midway through turning a pen, or not being able to get it tight enough to grip and stop the pen moving while it was turned. This thing stopped that straight away. Pressure comes straight from the tailstock through the bushings and barrel fittings to the mandrel top, removing the strain on the mandrel shaft and the thread at the nut (according to the blurb)
Worked for me.
