Comparison: Belay Devices

There are probably a hundred different belay devices on the market, yet around here, only two are commonly seen on climbers’ harness: the Black Diamond ATC Guide and the Petzl Reverso. A fairly new contender is the Mammut Smart Alpine, a tube-style device with the ability to autolock in the event of a leader fall, and a plate-style device rarely seen amongst recreational climbers but quite common with guides, the Camp Ovo.

The BD and Petzl device have undergone numerous permutations over the years. Both devices feature multiple friction modes and a ‘guide mode’ for bringing up seconds. The current version of the ATC Guide has cutouts in the sidewalls and a larger hole (in comparison to previous models) for the auto lock release. The Reverso 4 has scalloped sidewalls for weight savings, and as the Black Diamond device, an enlarged hole for the auto lock release. Both devices have a wire keeper loop.


The Mammut Smart Alpine is most easily described as a modified tube-style device. It can be used as a regular belay and rappel device with a single or double rope system, it also has an auto locking  ‘guide’ mode for bringing up seconds as well as the highlight feature, an auto locking mode for both belay and rappel. Due to this additional mode, the Mammut is both heavier and bulkier than the other two devices, though not overly so.

The Camp Ovo is the lightest and simplest device, in essence being a plate-type design with the addition of two large holes on either end allowing it to function in ‘guide mode.’ This is the easiest device to manage in ‘guide mode’ due to the size of the end holes and two spacious rope slots.

My scale shows the Ovo to be 57 grams, the Smart Alpine registers 118 grams, the Reverso comes in at 57 grams, while the ATC Guide weighs 90 grams.

They all perform the same functions so why compare the four designs? After almost a year of using all four devices on a rotating basis, I have come up with some inevitable comparisons.


The Smart Alpine is my favourite device for long belays and long days. It’s hands-free auto locking mode gives me the freedom to eat, drink, take pictures, pee, put on extra clothes, keep my hands warm or any number of other activities without worrying about catching the leader in case of a fall. And yes, I have tested the device in a leader fall auto lock scenario (with a backup) and yes, it does work. It is also an awesome device for long rappels with cold hands, the auto lock mode being almost too effective in stopping progress as soon as there’s any tension in the rope. Due to the nature of the design, feeding out slack and rappelling in auto lock mode takes some getting used to, but once mastered, it’s an easy change to adapt to.

It functions as expected in guide mode, though the long ‘arm’ containing the auto lock release hole provides extra leverage, making it easier than the other devices to let out slack to your followers. While Mammut recommends the device be used with ropes ranging from 7.5 – 9.5, I’ve found the device works best with thinner ropes, and prefer not to use it even with my 9.4 single. Otherwise, the slim design doesn’t ice up or clog with snow and my reservations about the durability of the plastic bits have been proven unfounded.


The Reverso and ATC Guide are hard to differentiate. They are almost identical in design, save for the orientation of the guide hole (the Reverso’s is in line with the rope slots, whereas the ATC’s is perpendicular). The biggest difference appears to be in the width of the rope slots, though both devices are rated for ropes of similar diameter: BD recommends 7.7 – 11 while Petzl states a minimum of 7.5 for half/twin systems and 8.9 for singles. In my usage, I have found the Petzl to work better with thinner ropes and the BD to brake better using thicker lines. The rope slots in the Petzl are so narrow that I often struggle to force a somewhat icy 9.4 through the openings, while the same rope slides smoothly into the BD’s slightly larger holes. Conversely, the larger openings in the BD create less friction with thin ropes (I’ve tried 8.2, 8.0 and 7.8s in both devices). I haven’t found the different guide hole orientations to present any functional benefit in use, and the auto lock release holes are very similar in size.


The Camp Ovo is a dream to belay seconds with. The large rope openings and spacious guide-mode holes make it quick and simple to set up, even with iced up ropes. Where the larger rope openings really come into play is when taking in rope. Whereas the other devices can bind up and feel a bit ‘tight’ the Ovo remains extremely smooth, even allowing for one-handed operation (i.e. pulling on the brake rope pulls through any slack). I’ve used it with ropes from 9.4 through to 7.8 without issues. The device is a bit more difficult to use when rappelling and lead belaying, as it doesn’t have the ‘keeper’ wire that keeps the BD and Petzl in place. That said, it works without issues with all diameters of ropes, and with all shapes and sizes of carabiners.

All four devices work well, and are equally capable of typical belay duty, bringing up seconds and the inevitable rappel. The ATC-Guide is my preferred device when using single ropes (i.e. 9.2 and over), the Reverso excels at the same duties but with double ropes (7.8 – 8.2), the Ovo is unsurpassed at bringing up seconds with all types of ropes and comes with me on every climb as a second belay device and a backup, and the Smart Alpine is my go-to for longer days when the auto-lock features allow (somewhat) hands-free operation while eating, drinking, staying warm, etc.

I wish I could pick just one, but having used all four, I’d be hard pressed to pick. Just as we as climbers use different ropes for different applications, so I use different belay devices with different ropes.

2 thoughts on “Comparison: Belay Devices

  1. Ryan S Mullins says:

    Like the post, and agree with damn near anything you say. My only point of contention is using the Ovo to belay a leader.

    Both the Ovo and the Kong Gigi it was based on were not designed or tested to belay a leader. The AMGA, manufacturers, and even place like Outdoor Gear Lab all recommend strongly against this. They are perfectly fine for rappels though, often being my preferred rap device on longer raps. Just be sure to use a friction hitch of some sort as a backup.

    • Raf says:

      Very interesting point Ryan, thanks.

      I’ll be at OR next week and will ask the Camp guys about this (I just checked the website and it is somewhat vague as to the usage of the device.)

      The Kong website has this to say about the Gigi when “Belaying the thirst [first, ed.] climber:”

      “In spite of the fact that Gi-Gi has not been expressly conceived as dynamic belayer for the first climber, it is used by some experts using two connectors.


      It is a delicate manoeuvre requiring skill and training.”

      So it sounds like it’s doable?

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