At Salomon, the S/Lab vest has long been the benchmark for ultra running: light, stable, invisible on the move. But one detail had been bugging long-distance trail runners for seasons: you couldn't grab a jacket from your back without stopping. With the S/Lab Ultra 12, released in early 2026 and built as a continuation of François D'Haene's work, the brand doesn't reinvent anything. It finally fixes that flaw, adds two liters and owns a price tag that stings. We put it through its paces.
The S/Lab Ultra 12 is a premium 12-liter hydration vest built for long ultras and highly self-sufficient outings, with the second-skin stability the S/Lab line is known for. Its real novelty is not technological but functional: a low back pocket reachable from the side, which finally lets you pull out a layer without taking the vest off. It delivers on fit with flying colors, far less so on value, with a €200 price tag that climbs to €230 with the quiver.
8.5 / 10 · RunMorph overall score
To understand what this vest represents, you need to look back. The Sense Pro 10, then the S/Lab Ultra 10, were benchmarks for stability, but they shared the same weakness: a back built around a large vertical pocket designed for volume and awkward to use on the move. To grab a waterproof jacket or a thermal layer, you often had to stop, contort yourself or even take the vest off. On an ultra where the weather shifts and the mandatory gear list is long, that kind of detail quickly becomes an irritant that breaks your rhythm.
At RunMorph, we see Salomon taking the pragmatic route rather than the spectacular one. The S/Lab Ultra 12 doesn't go back to the original system of the Salomon Adv Skin 12 with its large wraparound pockets. Instead, it adds a low back pocket, reachable from the side, that lets you stow or pull out a compressed jacket without removing the vest. It isn't a wraparound kangaroo pocket. It's side-rear access, but that's exactly the access that was missing. Volume goes from 10 to 12 liters, anchoring the model even more firmly in long-ultra territory.
| Brand | Salomon |
|---|---|
| Model | S/Lab Ultra 12 |
| Release | Early 2026 |
| Volume | 12 L |
| Empty weight | 205 g (295 g with the 2 soft flasks) |
| Sizes | XS to XL, unisex cut |
| Front pockets | 4 secure pockets, 2 soft flask sleeves, 2 zippered shoulder pockets, 1 removable water-repellent phone pocket |
| Back storage | 1 main compartment with snap-button top access, front zippered pocket, stretch tunnel pocket with dual side-rear access |
| Bladder | Compatible with a back reservoir (not included) |
| Soft flasks included | 2 x 500 mL, wide caps, high-flow valve |
| Fabrics | Lightweight multidirectional stretch, back mesh, seamless construction, PFC-free |
| Fit system | SensiFit construction, Quick Link sternum strap |
| Pole holder | Custom Quiver system (quiver sold separately) |
| Safety | Built-in whistle |
| UTMB mandatory gear | Compatible (with bladder and emergency blanket) |
| Official price | €200 (around €230 with the quiver) |
On the scale, 205 g empty for 12 liters is reasonable without being a record. For reference, the Compressport Ultrun Evo 10 V2 drops below 120 g, but with 10 liters and no back bladder compatibility. The S/Lab Ultra 12 plays a different game: it takes more gear, handles a reservoir and aims for long-range self-sufficiency rather than gram counting.
Fit is the signature of the S/Lab line. The SensiFit construction uses self-adjusting materials that wrap around the rib cage and spread the load over a large surface instead of concentrating it on the shoulders. The concrete result: the vest hugs your torso, doesn't bounce even when fully loaded, and disappears once you're up to speed. That's the model's real strength, and it accounts for a good part of its status.
The Quick Link sternum strap rounds things off. You adjust and tighten it in one move without stopping, and its elastic lets your chest breathe during hard efforts. The main fabric, stretchy and light, gives you a freedom of movement that's rare on a vest this size. At RunMorph, what stands out most is how consistent the fit stays, whether the pack is full at the start of a loop or nearly empty at the end of an aid stop, which isn't that common.
RunMorph's advice: a stable 12 L vest doesn't excuse you from learning how to distribute your load. Put the heaviest items (bladder, bars) as close to your back as possible and keep the front pockets for what you need right away. If you're new to self-sufficiency, train first with a lighter format like the Ultimate Direction Race Vest 6L before loading up 12 liters of gear.
We put the S/Lab Ultra 12 through mountain long runs of 3 to 6 hours and highly self-sufficient course recons, carrying a waterproof jacket, a thermal layer, a water reservoir and solid food. On that terrain, the vest is in its element. Stability is flawless on technical descents, exactly where many packs start to slap around. The two 500 mL soft flasks, with their wide caps, refill fast at aid stations and take ice cubes, a valuable detail in serious heat.
The novelty, that famous low back pocket reachable from the side, keeps its promise in use: pulling out gloves or stowing a compressed jacket on the move becomes possible, where the Ultra 10 forced you to stop. Be clear-eyed about the wording, though. This isn't a giant wraparound pocket like on the Adv Skin, and access takes a bit of gymnastics the first time. But the long-standing irritant is gone. On short, fast formats, on the other hand, this 12-liter volume and this level of equipment are clearly overkill: for a skyrace, a Black Diamond Distance 8 or a NNormal Race Vest 5L remain better choices.
Three 12-liter vests, three philosophies. The S/Lab Ultra 12 bets on second-skin fit and premium finish, the Adv Skin 12 on versatility and wraparound back access, and the Raidlight Ultralight 12L on low weight and Made in France construction at a gentler price.
| Criterion | S/Lab Ultra 12 | Salomon Adv Skin 12 | Raidlight Ultralight 12L |
|---|---|---|---|
| Volume | 12 L | 12 L | 12 L |
| Empty weight | 205 g | 244 g | 200 g |
| Soft flasks included | 2 x 500 mL | 2 x 500 mL | 2 x 600 mL |
| Back access on the run | Side-rear pocket | Wraparound pockets | Large stretch pocket |
| Fit | S/Lab second skin | Wraparound Sensifit | Micrometric Freelock |
| Price | €200 | €165 | €160 |
The verdict depends on how you use it. For pure fit and demanding technical descents, the S/Lab Ultra 12 takes the edge. For the best access to back-stowed gear and a more contained price, the Adv Skin 12 is still a formidable option. For low weight and your wallet, the Made in France Raidlight Ultralight 12L ticks a lot of boxes.
This is the obvious target. On an 80 km or a 100 miler with mandatory gear, changing weather and widely spaced aid stations, the S/Lab Ultra 12 excels: stability, capacity, and access you can finally use. It's the vest many runners have been waiting for since the Sense Pro 10.
For course recons, multi-hour mountain runs or semi-self-sufficient efforts, the vest really comes into its own. You carry what you need without feeling the pack shift around.
Here, we clearly advise against this model. For a short trail, a vertical kilometer or a fast skyrace, 12 liters and €200 miss the point. Look at a 5 to 8 L vest instead.
A vest is only as good as the preparation behind it. To build your self-sufficiency and absorb the mileage of your ultra build-up, from extending your long runs to managing pace on mountain formats, rely on a structured plan.
Explore RunMorph's trail and ultra training plans to turn your gear into performance.
You tame an ultra vest in training, never on race day. The right move is to get your body used to running loaded well before your goal race: bring the S/Lab Ultra 12 into your long runs early in your build-up, lightly packed at first, then with your actual race load. Test where the bladder sits, how you reach the back pocket on the move and how you handle the soft flasks over sessions lasting several hours. The RunMorph trail and ultra plans guide you through building volume and the specific long runs where breaking in this gear comes naturally.
The S/Lab Ultra 12 doesn't try to reinvent the hydration vest, and that's a good thing. It fixes the Ultra 10's most criticized flaw, adds two useful liters for long ultras, and keeps the second-skin fit that built the line's reputation. It's a pragmatic, mature evolution, cut for trail runners who know exactly what they carry. The only real obstacle is the price: at €200, and €230 with the quiver, it targets committed runners willing to pay for S/Lab finish and stability. For them, it's a safe bet. For everyone else, the Adv Skin 12 or the Raidlight Ultralight 12L offer more reasonable value for money.
RunMorph score: 8.5/10