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Review: The Rab Kaon Lightweight Insulated Jacket

It's one of the lightest and most durable insulated climbing jackets on the market

The Rab Kaon jacket is a lightweight insulated jacket that excels when weight and packability are paramount and when range of movement is imperative.

The Rab Kaon jacket is an excellent choice anytime you are looking for a lightweight insulating layer. It excels as an insulated piece to bring along on alpine objectives, summer multi-pitches, and a layering piece for cold weather climbing. Unlike many other insulated jackets, the Kaon is exceptionally compressible.

It has areas that Rab refers to as intelligent zoning where Pertex Quantum air panel inserts allow the jacket to breathe if you start to get hot while moving. The insulating features it offers, such as the high-loft hydrophobic down, quick-drying synthetic fill, and insulation free underarm sections, create an outstanding balance between warmth and not overheating while moving.

The keys to this jacket are its weight and ability to regulate temperature when climbing. With 800 fill European Goose Down in the body and quick-drying Stratus™ insulation in the shoulders and hips, even if you end up sweating a bit while moving, the synthetic insulation is placed in the most critical zones and will not lose its insulation value. The jacket is designed for climbers, stripped down with only one chest pocket and a slim fit to reduce weight and bulk.

I’ve been using the Kaon jacket for over 200 days, and it has accompanied me every day in the mountains. I found it the most beneficial when I wanted a small puffy on alpine climbing days, and multi-pitch rock climbs in the summer and fall.

In the last few months, I’ve used it as an outer layer on dry ice climbing days and as an insulation layer on colder days for both ice and mixed. In addition to climbing, I’ve used it for ski touring, trail-running, mountain biking, bike packing, and long-distance hiking.

The fact that it can fit into my running vest is appreciated when running up local peaks. It shines when winds increase after leaving the treeline when having a warmer insulated piece for the last several hundred meters to the summit is welcomed. The Kaon is lighter than most competitors, with increased breathability and freedom of movement, making it one of the most comfortable and versatile insulating layers I’ve owned.

Speaking with Rab athlete Benjamin Lieber after his recent first ascents in Alaska, he told me, “The packability is king, the Kaon can fit into your pocket. Pound for pound, it’s as good as it gets. I use it as my light puffy on warm summer alpine missions and then as a leader puffy in chilly weather alpine climbing or ice climbing. It’s my main insulating layer in the summer.”

Aaron Mulkey, another Rab athlete who is considered the monarch of ice climbing in Cody, Wyoming, loves the Kaon as well. He said, “It’s hard to leave at home or in the pack when it’s so light and warm.” On top of the mountain benefits, he’s also wearing it around town, saying, “I wear mine as an everyday jacket as well. It’s like wearing a sleeping bag but stylish.”

Rab Kaon Photo courtesy of Tim Banfield

Breathability: The breathability of the Kaon is outstanding for an insulated jacket. Pertex Quantum Air panels under the arms allow for exceptional heat regulation if you are wearing it and the output starts to get intense. In crucial locations where down is likely to wet out or be compressed by a backpack, the Kaon is filled with Stratus ™ insulation to maintain its insulation value and dry out quickly.

Movement: Range of motion is another area where the Kaon excels above its competitors. I’ve rarely noticed that the jacket was on as the underarm panels also allow for range of motion that I’ve appreciated on steeper rock routes during the summer and dry-tooling this fall.

Weight: The Kaon is one of the lightest insulated climbing jackets on the market. It’s not meant to be your jacket for the coldest days but excels as a three-season puffy and a mid-layer in winter. The Kaon weighs in at a mere 250 g (8.8 ounces). The Kaon is lighter and more compressible than comparable insulated jackets but offers features and a cut that they don’t. As a comparison, the Kaon’s weight is 250 g, and the Arc’teryx Nuclei FL is 325 g, while the comparable Patagonia Nano Puff Hoody is 363 g.

Features: The Kaon is designed to be a climbing jacket. It offers Atmos™ lightweight ripstop nylon outer fabric, uninsulated Pertex Quantum Air underarm panels for mobility, hydrophobic down, a down-filled hood, and Stratus™ synthetic insulation over shoulder areas, cuff area, and hips. It also comes equipped with a tiny stuff sack and low volume elasticized cuffs that do not interfere with climbing.

Cut: The Kaon is a slim cut, perfect for climbing where bulk matters, and great for any activity where you will be moving in the jacket like approaching ice climbs, cold weather trail running, and fat biking. The jacket’s length allows it to stay in place under a harness, and the hood fits over a helmet, which I find to be a key feature with lightweight jackets.

Value: At ~ $300, the Kaon is well priced compared to other industry-leading lightweight insulated jackets. The price is typically $50 to $150 less than the competition, and I haven’t had any durability issues yet after 150+ days of use.

Conclusion: The Rab Kaon is a solid choice for climbers looking for an extremely lightweight and warm jacket. Its size and weight make it a mandatory item for me every day out. Like Aaron Mulkey said, “It’s hard to leave at home or in the pack when it’s so light and warm.”

Very Compressible
Range of motion.
Slim fitting
800-fill hydrophobic down
Vented underarm panels
Climbers fit, slim, and stays under a harness
Hood fits over a helmet

No hand pockets, but it’s lightweight, so you lose these types of options.

Peter Hoang and Tim Banfield