Tuber with 'antlers'by Martijn Bruil on 01/31/2023
The master pro acts just like any other tuber style belay device ....with extra features. Its special features are the two protruding 'antlers' at the front and added holes in the side.
As specified by Grivel, the rope, or ropes could be quickly twisted behind the antlers, forcing the rope firmly into the friction grooves and adding friction to the Master pro. The extra fiction provided by the antlers is enough to completely block the rope after a fall. Never let go of the rope though! With a quick twist, the rope is twisted back and the Master pro works as any regular tubing belay device. The usage of the antlers is a welcoming feature when the climber is projecting or just 'resting' a lot.
Besides belaying from the body, the antlers don't have any special uses. According to Grivel, the antlers could be used for extra friction during abseiling or make the Master pro usable as an ascender. In practice, the Master pro adds enough friction as a tuber when abseiling. I have tried using the antlers, but the antlers add so much friction that I was basically by the Master pro only. Perhaps when carrying a heavy load or being a very tall and muscular climber is required for sufficiant usage of the antlers when abseiling?
Although the antlers have a good use by quiclky blocking the rope, I recon the antlers hook just a bit too shallow for the rope to stay into the antler's grip. With a bit of movement, the rope naturally comes out of the locked position and the added benefit ceases.
Using the Master pro for belaying one or two seconds in guide mode, I find the antlers awkward for lowering the second climber. According to Grivel, a sling or cordelette would web around the antlers and by moving it through the stance, one could 'unlock'the Master pro. In my opinion, the small 'biner hole' in the front of other tubers (such as the ATC guide or the Reverso) works way easier and smoother for lowering a second climber. Besides having difficulties lowering second climbers, I make sure to use a smal, diameter rope or a new rope as the Master pro is a true master for adding friction. Using older or thicker ropes, I rather belay with a munter hitch than using the Master pro in guide mode. This disadvantage only applies when using the guide mode though. I don't experience any difficulties with older or thicker ropes when belaying rather smooth as a tuber.
The second feature of the Master pro is the holes you will see in the sides of the device. These supposedely acts as a heat sink. Using other tubers, I never felt that heating my device isn't such a major problem, even after rappeling long distances. If youy experience is your rope melting due to excessive heat into your tuber, the Master pro may be just the belay device you need.
In short, The Master pro has quirky features, that benefit single pitch climbing and abseiling for the heavy climbers. Tot much for multi-pitching though.