The Mammut Smart is very light, very compact and a real value. For a day at the gym or crags, this device is a great, auto-locking belay device alternative to the standard belay device such as the Black Diamond ATC XP, which does not lock up. It is the same weight as most manual belay devices, meaning that you hardly notice it on the side of your harness.
The Smart took some getting used to. It has a tendency to lock up when throwing rope out fast to a leader. It was also one of our least favorite devices to lower with. For everyday lead belaying and lowering it works, but not nearly as smoothly as most other devices. Additionally, it does not work as an auto-block device, which the Cinch or GriGri do.
This device is recommended by its maker for much skinier ropes than the GriGri or Cinch. However, we found that the GriGri and Cinch actually locked up better on really a skinny rope than the Smart. So it just goes to show you that the "manufacturer-recommended rope diameter" only means so much. Read our the GriGri and Cinch reviews for a more detailed discussion on manufacturer recommended rope diameters.
Belaying in the gym? Hitting the crags for a day of leading and TRing? Looking for a great auto-locking device but dont want to spend the extra cash for a Trango Cinch of Petzl Gri Gri? The Smart is a great low-cost alternative to other auto-locking devices and works on ropes from 8.9mm to 10.5mm.
We took the Smart cragging in The Valley. It worked especially great for TRing. It would auto-lock off with ease, so we didnt get as worn out controlling the rope. When we handed the device to a friend to belay us, often we were short roped. It was not intuitive at first.
Chris Mac is curious to see how this works for short-fixing on big wall speed ascents. He is used to not bringing a GriGri or Cinch because they are too heavy to lead with. But the Smart is so light that it might be worth leading with and then self-belaying with while short fixing (not sure if the manufacturer recommends this).
A price of $30 for the Smart auto-locking device is a great deal. It is far less than the Petzl GriGri and Trango Cinch. It is not as versatile as the previously mentioned devices, but is great for the climber on a budget.