DMM Mantis belay device Review

© Dan Bailey

The Mantis is the "classic belay device made better", say DMM, and with its lightness, smooth handling and secure feel on a wide range of rope diameters, it's hard to argue with them. Shaped like DMM's Pivot, but without the hinged addition that enables it to be used in direct belaying 'guide' mode, the Mantis looks at first glance pretty simple. In essence it may be based on a plain old tube; but once you start using it, the thought that DMM have put into the details soon becomes obvious.

Lowering on a 9.7mm single - the deep rope grooves give plenty of grip  © Dan Bailey
Lowering on a 9.7mm single - the deep rope grooves give plenty of grip
© Dan Bailey

Size and weight

Hot forged, and then milled with a computer-controlled cutter to add detail and strip out excess metal, the Mantis is both compact in size and impressively light, weighing just 45g. In comparison with rival devices roughly comparable in size and general design, the Petzl Verso weighs 57g, and the Black Diamond ATC-XP is 64g - not far off 50% heavier. A few grams here or there may not sound like much in the scheme of things, but it soon adds up, and anyone who is making an effort to reduce the weight of their hardware is going to appreciate the lengths DMM have gone to here. Though the weight of your belay device is arguably less of an issue for general cragging, when it comes to mountain routes - and particularly in winter - I've rapidly come to appreciate the lightness of the Mantis.

It grips well on thin winter ropes  © Dan Bailey
It grips well on thin winter ropes
© Dan Bailey

Every gram counts on mountain routes  © Lorraine McCall
Every gram counts on mountain routes
© Lorraine McCall

Basic geometry

To allow for an optimium balance of smooth handling and braking friction, the rope slots are subtly tapered. Extra friction is added by the deep v-shaped rope slots. Grooved for additional grip, these do a great job when you need to hold a fall, or when feeding out rope slowly and in control (lowering a climber, for instance, or abseiling). Meanwhile, the shape of the rear of the Mantis means it doesn't tend to jam against the screwgate, so when the leader needs a lot of rope in a hurry I find paying out is quick and smooth, not jerky or grabby like it can be with some devices. DMM's Technical Director David Noddings explains:

"When we talk about the 'rear' of the device, that's the opposite end to the grooves, so the bit by your belly when belaying. This aspect has a very important angle and radii that work with the outgoing (to the climber) rope to gently pull the device away from the biner (lift-off) to encourage/allow smooth paying out. Quite often this is overlooked in other designs, but it really is important: the devil is in the detail!"

Belaying a leader - paying out is smooth and fast  © Dan Bailey
Belaying a leader - paying out is smooth and fast
© Dan Bailey

Rope diameters and handling


  • With a single rope: 8.5mm - 11mm
  • With a pair of doubles or twins: 7.3mm - 9.2mm

Abbing on a 9mm - smooth and easily controlled  © Dan Bailey
Abbing on a 9mm - smooth and easily controlled
© Dan Bailey

Belaying in big gloves on a pair of 8.5mm winter ropes; wrestling with fat furry cables down at the wall; sport climbing on a range of ropes from 9.6mm - 10mm; cragging with half ropes; top roping kids; abseiling; classic mountaineering days with a single rope - pretty much whatever I've been up to over the last few months, the Mantis has been in use. Its geometry accommodates an impressive range of rope diameters, and in use it feels smooth taking in and paying out even on an ancient 11mm that I excavated from the bottom of the cupboard. On the other hand thanks to the tapered rope grooves, with their sculpted channels for extra friction, the holding power feels reassuring - and even on slick skinny ropes, I've always felt things were safely under control when belaying.

Belaying a leader with double ropes   © Dan Bailey
Belaying a leader with double ropes
© Dan Bailey

Bringing up a second with the Mantis  © Dan Bailey
Bringing up a second with the Mantis
© Dan Bailey

The 7.3 - 11mm range of the Mantis compares well with rival devices (the BD ATC-XP for instance is 7.7mm - 11mm, while the Petzl Verso is 7.5mm - 11mm). Since it suits more or less any rope size that the average climber is likely to encounter, this is pretty much the epitome of an all-round belay device.


OK, there's not a lot to it. But it's light, it offers loads of grip for secure belaying, and it works smoothly on a wide range of rope diameters... what's not to like? If you're after a simple, effective and versatile belay device - and if you don't require the option of a guide plate mode - then the Mantis has to be one of the best choices currently available. I take mine everywhere.

DMM say:

The classic belay device made better. Using the same high performance internal geometry as the Pivot, the Mantis is an incredibly lightweight belay device for use with either single or half ropes in situations where direct belaying is not required; perfect for the climbing wall and general cragging. The carefully sculpted rope grooves offer a greater grip on ropes from 7.3mm to 11m, the rope slots allow easy loading, and the rear of the device ensures adequate lift-off for snag-free paying out. If you are after a lightweight, high performance all-rounder, then the Mantis fits the bill perfectly.

  • More effective in paying out rope
  • More comfortable for top-rope belays
  • Even safer thanks to the V-Proof System
  • Compatible with ropes from 7.3mm to 11mm
  • More ergonomic thanks to the new shape of the outer body

For more info see:

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3 Mar, 2017
What's it like used 'backwards' (dead rope over the smooth side, rather than the grooves)? Any better for thicker ropes, or unnecessary? Do DMM have an opinion on whether it's even a good idea or not?
3 Mar, 2017
Hurrah-and about time! Would happily have bought one of these a year or so ago when they were first announced. Ended up with the pivot instead, which is lovely to belay with. I reckon the mantis would be great for 99% of the time for me, but I can't justify buying another shiny toy now I have my pivot (can't I?!?)
3 Mar, 2017
Bought one at UCR yesterday as I left my main belay device at the place in Italy, and was impressed with it. Was using a 10mm single and it was smooth to pay out - was grabby a couple of times, but I think that is down to using a new device as much as anything else. Certainly an improvement on my previous tuber device...
3 Mar, 2017
I'm surprised your partners have not all collected their Chips! I'll get me coat.......
3 Mar, 2017

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