To continue my quest to wast.... I mean invest more money on climbing, I started ice climbing last winter. So far, I only had to sell my left kidney and what I find at home yet don't expect. But I digress.
I quickly realized I don't have a good midlayer/outerlayer jacket, because I was shivering during belaying. After asking around, I picked Xenon (not this one, I bought BackCountry exclusive one, because it was cheaper). So far, I love it and it saddens me that I have to put it away, because winter is over.
It is really light, yet surprisingly warm. Maybe too warm.
And there lies it's only fault: it's too good of insulator and not breathable.
But it's hell a lot better than freezing.

Rab comes through again with a smart, USABLE, versatile jacket. Quality is there too. Lightweight, more of an athletic fit (you can put light layers under it just fine); compressible in the backpack or ski bag for layering under a shell. As a layering jacket, if you find that down is just too much heat, this is your other alternative. No hybrid fabrics on sides or pits to dump heat quickly but overheating hasn't been a problem. And don't underestimate the power of Pertex Quantum as the outer ultra-lightweight fabric--very strong, wind resistant, water resistant, and helps hold in the heat.

I own lots of Rab clothing as I'm 6'4" 175 and their size large fits great- long arms and an athletic fit in the midsection. If you're tall and slim u know what I'm talking about... I expected the same with this jacket but was disappointed to find the fit more "regular" and not slim fitting in the mid-section thus greatly reducing its thermal ability (I've learned my lesson with other brands). I returned it. However if you looking for a synthetic jacket, this one has been voted the #1 synthetic jacket by Outdoorgearlab for the past several years so I have no negatives against its quality/thermal ability.

I have lightly used the jacket so far and it seems very warm and packs down small. I did extensive research before this purchase and it seems to be all it's cracked up to be. I want to note that the color ebony looks more like dark blue. I asked several people what color it looked like to them and they all said navy blue. I always wear medium shirts and that's what size I bought. It's a nice slim fit. I wouldn't be able to wear too much underneath it.

I purchased this to be used as a backcountry skiing/climbing belay jacket. Unfortunately it's not winter yet, so I haven't been able to test it out in the snow. On the other hand, it's been awesome for chilly days in the office and those frigid fall mornings in the Uintas. I can already tell it's super light weight and will pack away well.

This was a daily wear jacket in NYC for the winter of 2015. For temperatures below 40, the jacket alone is not sufficient if you are just wearing a button down shirt or sweater.

The jacket is very attractive looking, the orange lining on blue works very well.

Pockets are generously sized (and perfectly lined), and hood is nice and snug. Fit is normal, not slim. I am 5'8, 155 with a slim athletic build; small fits decently. Arms are a bit too long for me, and that is usually not the case for my clothes.

I've taken it camping a few times, and it's great to be able to throw a synthetic into the washer without having to worry about it. No snagging on branches too - which was a nice surprise.

For the price, if you are looking for lightweight, decently warm jacket that packs well - this is a solid choice (esp at current discounted prices).

This insulating layer is an essential item for me. It is likely the most versatile layer that I own. I have worn it in a wide variety of conditions and seasons - typically at a high level of exertion. It has an impressive amount of breathability - which is crucial since the times I'm wearing this layer nearly always involve aerobic efforts be it rock climbing, alpine climbing, snowboarding, or backpacking. It's nearly always a "just-right" layer that I'll toss on over a tech t-shirt and +/- softshell. I've also been very pleased with its warmth during snow/rain in the cascades over the rab baseline fleece and under a hardshell with +/- patagonia capilene as a baselayer. I'm a slender guy, with wider shoulders and long arms - Rab fits me hands-down, far-and-away better than any other brand and the xenon hoody is no exception - It's not excessively baggy in the midsection, it's not restricting in the shoulders nor too short in the arms. Other jackets I have tried seem like they're made for much larger abdominal girths than mine and inevitably result in too much fabric bunching about my waist (right where I need access to my harness) and the typical trade-off for fitting around the waist is not enough around the chest/shoulders while the your midriff and wrists are exposed. I've had NONE of those issues with Rab. If you have similar sizing problems I strongly encourage you to check out Rab gear - it's like gear made for climber-sized people. The hood fits easily over my climbing helmet and does a fantastic job keeping my head warm. The hoody is lightweight and packs down nicely (into the front chest pocket if you'd like), it sheds water quite well (not designed to be waterproof mind you), and seems to be more durable than the fabric feels like it should be as it has survived lots of scraping and dragging. I wear this thing all the time, not just during outdoor pursuits - around town, on the way to work, walking the dog, etc. I love this thing.

Fits well. Very warm. Feels nice and soft. The cut on it is great. Hood fits perfectly.

I bought this because I wanted something I could wear on my harness, but easily throw on while I was waiting two hours at a belay for my slow partner to finish his aid lead. I also needed something that could stand up to some rain, so down was out. This thing fits the bill and has exceeded my expectations!

I guide in the Tetons all summer. Any day that's going to be potentially stormy, which tends to me most days up high, this is the go-to jacket for me. I love that I can put a light shell over it when it's raining and cold and not have to worry about getting it damp- unlike down products. And since it's almost as light other down jackets, and packs almost as small, it makes it an easy choice to go with this tried and true piece. I'd say I've been comfortable in this jacket (with a med weight fleece under it) in temps down to about 10*F in the Tetons.



For how light it is, it takes an incredible amount of abuse. I've guided the Grand Teton with it over a dozen times and it's showing no signs of ware thus far.



The pic is of me summiting Tocllarraju (19,900 feet) in Peru. It's also been by go-to jacket when I work down there. When the temps drop below 10*F, I put the Rab Neutrino down jacket over it and I'm good for temps down to -30*F. And because the Xenon is synthetic, I can put on a big down parka over it and not worry about compressing the Primaloft, it keeps it's loft even when you stack layers on top of it, unlike a down jacket would.



Highly recommended!

Bought the ebony color (is a dark blue) in medium. To help people figuring out sizes, either this jacket is for people with long arms, or I have short arms. The medium fits my body well, it is an athletic fit so you can wear it as an under layer if it gets very cold, I've only used it above freezing. Now my arms measure to a size small, so the arms are a little longer than I would ideally want, but it isn't to the point where it's a problem.

Tldr: super warm, super light, make sure to match your measurements with Rab's chart!

I really like this jacket. It packs up super compact, and seems to be just the right amount of warm. I wish it had some vents for the pits, and wearing the hood looks really goofy if you're not wearing a helmet. Otherwise, it's sweet. The large is right for me.

Comfortable, packs down to almost nothing, looks great!

Kept me warm at night up to camp II on Mercedario (10,000ft Northern Andes), and in Red Rock, Nevada with snowy conditions. When layered with a Patagonia Cap 2 and R1 below, and light MHW softshell overtop I've stayed bearably warm to the teens if I'm moving and wearing a hat/buff.

When I began my research for a jacket I debated between the Rab Xenon X and the Atom LT. In the end I decided to go with this one based on the it's status as the Editor's Choice at Outdoor Gear Lab, the fact that it did not have the fleece sides, and the chest pocket. So far the lowest temperature I've worn the jacket in was mid to low 30s and the jacket did a great job keeping me warm. I have worn the jacket in a light drizzle, nothing too wet, and it obviously kept me dry. I'll update this review later if I put it through a heavier rain. As others have mentioned the hood is ugly but is very comfortable and I'm happier to be with than without. When I was deciding on jackets I didn't think I'd use the chest pocket much but I've actually come to like this quite a bit and I now consider this a significant advantage over the Atom LT. The pocket makes it super easy to pack and throw in my bag. The fleece lining around the mouth is also a nice touch.

The only thing I don't like about this jacket is the fine toothed zipper. While it does look good and is probably lighter than other zippers I can't help but wonder how durable it will be over the years. Time will tell and I'll update the review if I have troubles with it.

The lack of breathable fleece on the sides is both a blessing and a curse. In cold weather when it's windy I'm covered. But because the jacket insulates well I have had to unzip from time to time to let out heat.

Negatives: More of a personal taste but I wish the jacket were more fitted as it looks somewhat baggy on me. Unfortunate no stores in my area (Atlanta) carry the jacket as I would have liked to try different sizes to try something less baggy. More color options would also be nice.

Chest: 40 inches

Overall I'm very satisfied with my purchase.

Bought this jacket as both an insulating layer and by itself. It has performed perfectly in both scenarios. Have used it under my hard shell during extreme alpine conditions and was almost too warm! Have used it hiking in very windy conditions and it was warm and very windproof. I am 6'3" and 195lbs, athletic build and the large fit perfectly. Originally bought the XL but returned it because it was too large in the torso. Awesome jacket!

Purchase this jacket looking for a lightweight belay /over-jacket for rock and alpine climbing.
Good: I am 5"10, 150lbs and medium fits my torso and arms fine, both over and under an Arcteryx Alpha AR shell. It is extremely lightweight and comfortable.
Bad: The fit over my Sirocco climbing helmet is too close. The hood pushes the helmet so firmly into my head, I'll never be able to wear it for any length of time. I have had to return a First Ascend hoody for the same reason so perhaps the helmet is the problem here. Other lower profile helmets might work better. Second issue is that the zipper is small and feels insubstantial. My first zip, I didn't have the zipper pin fully engaged with the zipper box and it slide up halfway on one side. It is difficult to engage with gloves on, and I bet with cold hands too. Hood shape is a bit like a crusader's helmet if that matters to you.

I have had one of these for some time now and love it. I wear it primarily in either a casual setting, but I also carry it up multipitch rock climbs quite a bit. It is lighter and as small as my rain jacket when packed, and way warmer. For a multipitch layer, i highly recommend it. I do have some cord (and duct tape...) backing up the carabiner clip loop, but only because I'm paranoid of getting it caught on something and tearing it.