Rab Photon X Review

The Photon X is Rab’s premier synthetic belay jacket, insulated with PrimaLoft® Gold Insulation Active and aimed squarely at the alpine or winter climber needing a ‘bomber’ jacket for foul conditions.

The idea of insulated jackets for alpine and winter climbing has been around for a long while but the ‘belay jacket’ concept can be traced back a little under 20 years to Mark Twight’s iconic book ‘Extreme Alpinism’. In it he prescribes a trim, light, breathable, flexible action suite of fleece light shell etc worn whilst moving which didn’t cause you to sweat excessively and a big synthetic jacket donned over this when you stop to belay. Prior to this people had been layering up or down under their shells. This was slow and fiddly, take your waterproof off, pop another fleece on, pop the waterproof back on (before it blows away!), loosen your harness, tuck your fleece and waterproof under the harness etc. Twight’s system on the other hand was fool proof and fast.

A belay jacket needs to provide warmth and compressibility, as it must keep you warm whilst also having to be stuffed into your sac or a stuff-sac clipped to your harness and carried on route. There are two main types of insulation that fit this criteria; down and synthetic. Down is unbeatable in the warmth/weight/compressibility stakes but has a fatal flaw, its vulnerability to the wet. Recent advances in hydrophobic down have mitigated this in some circumstances but not in the abusive world that a belay jacket is expected to live. Modern synthetic fills are far more compressible than their bulky predecessors and hold little moisture making them ideal for the typical abuse a belay jacket experiences where you may be throwing it on over a wet shell whilst spindrift piles down on you and 20 minutes later stuffing it into a pack along with another generous helping of the same spindrift! If you’ve got properly cold on the belay you may well start climbing in your belay jacket as well so it can’t be too delicate or so bulky you cant see your feet!

The Photon X in action below the corner of Auricle.

Belay jackets may also serve double duty on multi day routes or on over night bivis to boost sleep insulation. In some circumstances they can form an integral part of a sleep system either paired with a pied d’elephant or boosting a lightweight sleeping bag helping to save weight and bulk in the pack. So it might help to think of your belay jacket a bit like a ‘Dales farmer’s Landrover – it has a multitude of jobs to do most involving abuse and it can expect little in the way of TLC whilst ‘on the job’ especially if you climb in that uniquely ‘entertaining’ environment that is Scottish winter!

Photon X in its quality stuff sac – 678g

So what makes a good belay jacket? Well like any piece of kit there will be personal preferences and prejudices but some factors will be pretty universal.

  • It must be warm enough.
  • It must compress well.
  • Easy to get on and off over your climbing kit.
  • A hood that easily fits over a helmet (and your shell hood).
  • Robust – doesn’t need babying on the route.

Beyond that preferences for insulation type, cuff closure, pocket arrangement, single double ended zipper etc. are all fodder for a good pub discussion. The Photon X is certainly sufficiently robust the Pertex® Quantum Pro outer sheds spindrift and dampness and I’ve yet to put a hole in it with carelessly handled tools so it seems to strike a good balance between lightness and durability. The PrimaLoft® Gold Insulation Active is zoned with a lighter weight in the side panels and arms and heavier on the torso – this is a very warm synthetic jacket and more than a match for any of the Scottish conditions I’ve encountered so far this year (down to minus 27C with windchill – nose hair freezing weather!). The hood is amongst the best I’ve used easily pulling up over a helmet with my shell hood already up and zipping up to cocoon me from the maelstrom. The hood adjusts with a simple rear pull cord which is easy to use with gloves and also obviates the risk of being ‘whipped’ by front hood draw cords. For want of a better word the tailoring of the hood emphasises the quality of Rab’s designers and you realise just what a difference the little details make. Something I didn’t notice till I’d used the Photon X for a few sessions was the little collar or baffle at the back of the neck which really seals in the warmth but also seals out spindrift if you don’t pull the hood up – brilliant! Fit wise the Photon X will go over my ‘full on’ cold climbing layers: base, two mid-layers and heavy shell fine but the hem (arse!) area can get a bit snug with a full mixed rack big hexes and cams in the ‘Gorms. Sleeve length is excellent but a little more cuff width would help prevent sleeve inversions when puling the jacket off quickly with gloves on. To be fair I’m a 36″ chest and I went for a size small which is 37″ but in retrospect I should probably have sized up to a medium which would solve both these issues. I’ve climbed a few easy pitches in the Photon X and it’s not too bulky or restrictive and survived the scraps undamaged. Besides the basics that Rab have clearly got dialled in there are a number of nice design features which make belay life easier. The pocket arrangement is pretty standard in good belay jackets, two external hand warmers an external chest pockets (stuff some food in here!) and two internal drop in mesh pockets above the hem which I use for gloves or quick access to the guide on a long belay. Another nice touch is that along with an easy to use double ended main zipper there is a press stud at the hem so you can effectively unzip the upward zip pull to access your belay plate and then fasten the press stud beneath the belay device so that the hem doesn’t flap and seals in precious warmth. In reality I rarely use this feature but other folk might and it’s nice to have the option. Finally the supplied stuff bag is generous enough to allow easy stuffing of a damp jacket and includes a bomber clip in loop and a pull handle on the base for easy extraction of the jacket.

Note neck baffle/collar, easy pull double ended zip and press stud to allow fastening beneath belay device.

In Use
The Photon X has proven excellent so far, it has pretty much all the features you could want in a belay jacket and is plenty warm enough for anything the Scottish season will throw at you. It easily compresses into my 30litre sac along with all the other paraphernalia for a long day mixed climbing. I’ve used on the Ben, in the Northern Corries and Glen Coe on everything from classic ridges to more technical mixed ‘scratching’ routes. A good belay jacket like the Photon X lets you focus on the climbing in minimal layers knowing you won’t chill when you stop because your big jacket is there. Being synthetic it absorbed little moisture and dried quickly in the hut drying rooms or over the back of the chair in the pub. We’re now into February and it still looks ‘as new’ with no sign of damage from abrasive granite or pointy ice screws (chance would be a fine thing this season!) tools or terriers! If there was one thing I’d add to the Photon X it would be a large clip in loop so you could clip the jacket to a belay when swapping over on cramped stances – not essential but a bit of reassurance for the clumsy when its blowing a hoolie!


  • Robust
  • Compressible
  • Great Design


  • Best size up if you’re near the upper end of the size range

SRP £225.00

Stockists Rab Equipment

Richie is the enthusiastic amateur of the team. Enjoying all aspects of climbing but especially alpine, winter and his local grit . Having managed to survive the vagaries of both fluorescent Koflachs and rainbow tights in the 80s he looks forward to an even more stylish future. A shady past in mountain marathons and adventure races, including the Marathon des Sables, means he’s an advocate of fast and light. Though the former is debatable if you’ve seen him on a tricky lead!

Disclaimer – CGR reviewers are never paid to provide a review and the website does not take advertising. We are a bunch of keen climbers and travellers that accept sample products and offer an honest and independent review of the item. The reviewer will often keep the sample after reviewing it for both hygiene reasons and more often they’re in no fit state to return!

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