TRE popular

The other guys pretty much sum up the details. This is a VERY nice device. I do not think it to be complicated as far as the actual theory and use of the device, but when you first use it, it seems awkward. Do not fret - Give it a little time, and with use and some tinkering, this is possibly one of the best devices I have seen. It is substantially more expensive now, maybe from the upgraded material, but that is not really important for such a device. It is so smooth, when I first used it to belay a second from the anchor, I worried that it would not catch a fall, but it does and well. A must for multi-pitch, really nice for twin/double, and it even rappels well to!

I recently got one of these and it's a pretty slick device. Looking at it, it's not incredibly obvious how it works, but after a few minutes of looking at it, you'll just "get it."

When you do understand how it works, you see what a useful device it is. It locks up with the slightest pressure on the brake side of the rope. You could literally be holding the brake hand of the belay at a bad angle with a pinky finger and catch the person with virtually no effort.

But that does NOT mean this is an autolocking device. If you have your brake hand off the rope it may not lock up. After playing around with it for quite awhile, I think I've figured out what determines whether or not it will lock when the brake hand is off the rope. It needs a sharp jerk to lock up with the brake hand off. Thus is locks up when a leader falls, but not when toproping on a high friction power point with a tight belay. If you keep a loose belay while toproping it will lock up, but not if you keep a tight belay. The harder the climber falls, the more likely it will lock up too -- if the climber just gets pumped and slowly lets go, you better have your break hand on the rope.

Overall, a very useful and great product, but you have to know it's limitations.

AFAIK they changed the materials in the new model to improve longevity.

I've had this device for quite awhile now. When new, I loved this thing. It really does perform great. However, after a couple years of good use it does not effectively lock down on most ropes under 10 mil. I have subsequently semi-retired it, since I rarely climb on anything thicker. I have tried to tinker with it and restore it's former performance, to no avail. There is plenty of material left at the wear indicators, the rope grooves have just gotten polished enough that it doesn't grab. Based on my experience, I'd rate it great on performance and poor on longevity= good.

Best belay/rappel device I've ever used. It is manufactured by TRE Pfullingen (www.tre-pfullingen.de), distributed in the US by PMI.