Review: Rab Xenon X

U.K.-based Rab has a long history of designing quality, performance-oriented products for the harshest of conditions (or “connies,” as the British would say). And when rain and cold are constantly in the forecast, there’s simply no match for a synthetic jacket. Enter the Rab Xenon X Hoodie. Warm, windproof, and durable, this layer is lightweight and packable to boot—a true climber’s dream. I took the Xenon X bouldering in Bishop, cragging in North Carolina, and down to Patagonia for the Austral summer, and found myself consistently reaching for it over my down jackets or lighter weight wind shirts. Below I break down the Xenon X’s warmth, water and wind resistance, weight and packability, durability, fit and sizing, and more. To see how the Rab Xenon X stacks up, see our article on the best synthetic jackets.
 

Performance

Warmth

With top-of-the-line PrimaLoft Gold Active insulation (60g) and a windproof 20-denier Pertex Quantum shell, the Xenon X is one of the warmer synthetic jackets I’ve worn. Its baffle-free construction means less air sneaks through small stitch holes. Elastic cuffs, a snug hood, drawcord hem, and over-the-nose zipper also help keep warm air in and cold air out. The Xenon X is slightly warmer than baffled jackets also insulated with PrimaLoft Gold, such as the Patagonia Nano Puff and the Outdoor Research Cathode, but still no match for a heavier jacket like the Patagonia Hyper Puff with its 100g fill.

Water and Wind Resistance

With its baffle-free design and windproof and water-resistant Pertex Quantum shell, the Xenon X offers a high degree of weatherproofing. The shell is one of the most wind resistant synthetic layers I’ve worn, more than the crowd-favorite Arc’teryx Atom LT’s shell with its exposed side fleece panels. It will keep out a light rain but expect the Xenon X to soak through with heavy or incessant precipitation. It again beats out the Atom in this regard but offers significantly less water-resistance than Arc’teryx’s tougher Nuclei. Overall, the Xenon X combines considerable weather protection with lightweight, packable design better than most jackets. This makes it a great do-everything layer for multi-pitch rock climbing—I bring it along on iffy weather days as a combined wind jacket, rain shell, and warm belay layer.

Breathability

The Xenon X lags behind the competition in one vital category: breathability. You would expect the Xenon X’s PrimaLoft Gold Active insulation to offer greater breathability than jackets with standard PrimaLoft Gold, but putting the Xenon X to test on a cold-day run, I sweated out of the jacket almost immediately. And unfortunately, unlike other jackets like the Patagonia Nano-Air, the Xenon X has a shiny, nylon lining that sticks to the skin with just the smallest bit of sweat. For high-output pursuits, we recommend the highly breathable Arc’teryx Proton AR or Outdoor Research Ascendant jackets instead.

Weight and Packability

The Xenon X clocks in at 10.6 ounces for a women's medium and runs about middle of the pack in terms of its weight-to-warmth ratio. It is 2.5 ounces heavier than the Patagonia Micro Puff Hoody (made with PlumaFill insulation) but over 4 oz. lighter than the Black Diamond First Light Hoody (made with PrimaLoft Silver insulation). Patagonia’s Nano-Air is an ounce heavier than the Xenon X and offers more durability, breathability, and roughly the same warmth, but it is not packable. And this is where the Xenon X stands out. The jacket stuffs into its chest pocket, making it a much better on-the-harness choice than most synthetic jackets. It is only matched in this regard by the Patagonia Micro Puff Hoody (which, to be clear, is less durable than the Xenon X).

Comfort

The Xenon X offers instant warmth in a soft fabric reminiscent of a cozy sleeping bag. Lacking the baffling seen on most synthetically insulated jackets, it feels more lofty and fluffy than its competition. I grew to love the pockets on the Xenon X, large enough to bury my hands in and insulated on both the inside and outside for maximum warmth. Additionally, this jacket sports a fleece chin guard and snug-fitting under-the-helmet hood, so you can really batten down the hatches in the cold and wind.

Durability

For climbers constantly brushing up against sharp rock, durability is a main requirement in an insulated jacket. This is where the Xenon X absolutely shines. I wore this jacket while bouldering on gritty sandstone, climbing multi-pitch quartzite, and groveling up granite off-width cracks. The result? One single abrasion in the 20D Pertex Quantum shell. This might be the first time I’ve worn a lightweight, insulated jacket for over a year without totally thrashing it. The Xenon X is about as durable as it gets for its weight and packability—much hardier than the Patagonia Micro Puff or The North Face ThermoBall. Jackets such as Patagonia’s Nano-Air and The North Face's Ventrix are slightly more durable than the Xenon X, but they are noticeably bulkier.

Fit and Sizing

The Xenon X is billed as a slim-fitting jacket, perfect for layering under a technical shell or wearing while climbing. It fits true to size, but if you’re looking to wear bulky layers underneath, I recommend sizing up. The hem of the jacket drops slightly lower in the back, allowing it to stay tucked under my harness securely. The fit is not at all boxy like The North Face ThermoBall or even the Patagonia Nano Puff. It sports a sleek, slim, and simple design.

Men's Version

For this review, we tested the women’s version of the Rab Xenon X. Rab also makes the Xenon X in a men’s model, which weighs slightly more (12 ounces), comes in different colorways, and has the same overall design. This jacket is also priced at $235.

What We Like

• The outer fabric is highly durable and abrasion resistant, without sacrificing weight or packability.
• Slim-fit makes this jacket perfect for layering under a shell or wearing while climbing.
• For a jacket that packs into its chest pocket, the Xenon X is incredibly warm, lightweight, and weather resistant.

What We Don't

• Not as breathable as many other synthetics like the Patagonia Nano-Air and The North Face Ventrix.
• With a sleek, alpine-ready design and lack of color options, this jacket is not ideal for casual use.
• The warmth-to-weight ratio is great but not the best, topped by jackets like the Patagonia Micro Puff.

Comparison Table

The Competition

Within the synthetic jacket market, the Xenon X does not prevail in any single category. It’s not the lightest on the market and not the most packable. It’s neither the warmest nor the most weatherproof. And it’s definitely not the most breathable. That said, the Xenon X does a better job than most layers at ticking all of the boxes relatively well.

Among top rivals, Patagonia’s Micro Puff is a standout favorite in the ultralight and climbing community. It’s super lightweight, undercutting the Xenon X by more than 2 ounces, and it packs down noticeably smaller (for more information, see our in-depth Micro Puff review). But the Xenon X offers similar levels of warmth and weather protection at a $60 savings. Plus, its 20D Pertex shell is more durable than the Micro Puff’s 10D Pertex. Both are technical jackets that excel in the backcountry. A decision between the two will likely come down to priorities, but the Xenon X’s upgrade in tear resistance gives it the edge on our synthetic jacket round-up.

If breathability is important, we’d recommend checking out The North Face’s Ventrix or Patagonia’s Nano-Air jackets. Both feature air-permeable shells and unique insulation designs that do an impressive job of regulating your body temperature. Further, the Ventrix and Nano-Air have built-in stretch that is more comfortable for everyday wear than the Xenon X. But, the Xenon X offers superior wind and weather protection, weighs less, and packs down much smaller. If you want a synthetic jacket for high-output uses, we recommend the Ventrix or Nano-Air. But as a layer to keep you warm and cozy in remote places, the Xenon X is the better choice.