Summary: Some compromises and not a workhorse rain jacket for bad conditions, but light, compact, and effective enough to carry as a just-in-case piece.

- Fit is cut close and a bit short. I'm an athletic 6', 200, 44" chest to around a 35" waist with big shoulders, about a 20.5" torso length for backpacks. My typical sleeve length is around a 34/35. I own the large. Enough for some layering, but nothing too bulky (a close-cut fleece would work, my down puffy billows and gathers). It runs a bit short in the torso, which is my main complaint. When moving around, the jacket pulls up on my torso and exposes lower part of my waist/midriff.

- This thing is unbelievably light at 6 oz, and packs down small into a dedicated pocket. Super impressive at this price point. There are more breathable, lighter options but they retail a good $100-150 more.

- No vents. Get stuffy in high output activity.

- Really bare bones on the features. No hand pockets (one Napoleon pocket), and no cinches on the cuffs. Hood is surprisingly functional for how bare bones it is, but not as customizable as a more full-featured jacket.

- Pretty waterproof (Pertex Shield + is rated at 20k mm waterproofing), but will still wet through in bad conditions. It's also so thin that it can 'feel' wet in a downpour even though water isn't making it through the membrane.

- Blocks wind, but requires an insulating layer if it gets really bad.

Would give it 5 stars if it was cut a little longer. I carry mine around with me everyday in San Francisco or on late spring/summer hikes, just in case I need it. For hikes I expect to run into rainy conditions, I take a burlier, more fully featured jacket (but heavier) jacket.

Took this jacket on weekend trip with a soggy forecast, and it kept me dry without issue. I'm 5'8", 145lbs, and the small fit great, wasn't too big by itself, but I could still fit it over a light down jacket without issue for added warmth. It's a no frills rain shell, but has fully taped seams and zipper. No hand pockets, but there is a chest pocket for sunglasses or a phone. It packs down small, and didn't take up any room in my pack. There are more technical fabric that will breathe better if you're doing high intensity stuff, but if you just need something to keep you dry in a pinch, or on a hike, this will do that well.

Great, lightweight jacket. I wanted something I could toss in a backpack and wear over other layers of the weather got bad. This jacket fits great, moves well, and you can pack it away when you don't need it.

I bought this for a friend traveling around South East Asia and so far so good! True to size and keeps him dry.

Great ad shedding rain, even while on a bike. I purchased a large, which is slightly bigger than I'd like if wearing just a t-shirt. The large does offer enough room to layer up with a baselayer, or a lightweight puffy jacket. Construction of the jacket is good overall.

Jacket can be used in a few ways
- rain jacket
- sweatshirt underneath make it quit warm and function as a insulated wind breaker
Fit: Im 5'8 167lbs M was perfect i got it when i was maybe 5'6 135lbs and it still fit perfect. greater then 5'9 i would suggest large especially if you wearing layers underneath.
Durability: 9/10
-It is light may rip if gets snagged on a piece of metal or something but not from tree branches or things like that.
- I have worn this in complete downpour i was completely dry and the pockets and zippers are watertight my phone in the pocket completely dry
Breathability : 8/10 (its a rain jacket...)
Overall: Willing to bet I would remain dry even after a 100 gal of water was dumped on my head. It packs small to the size of my fist although do not store that way.can be used in many way i would totally buy this again i have had it at least 3 years with no issues looks like new an I have used it over 40 days worth of wearing.

I own the hooded Filament down jacket (med) and love it, but when I ordered the Helium II jacket in the same size I was surprised to find out that the shell did not envelope the puffy. It’s lightweight and tougher than competitors but taking two inches off of the torso length is a cop out!

A great minimalist jacket that keeps me dry day after day in the backcountry. Everything from peak bagging, to a day at the crag, this jacket will perform tirelessly. Very durable for the weight and you'll forget it's in your pack.

If you Google this jacket, it has made its way onto gear lists for bikepacking, thru hiking, trekking and pretty much anything where Ultralight gear is paramount. It was my go to rain/snow protection on a recent S24O and it left me feeling confident as I pedaled through the night with intermittent light rain and snow flurry’s at 9000 feet.

This is a perfect ultralight rain layer. I love how small it packs down. The water resistant zipper is a little difficult to zip up and down but that may be because its brand new!

I love this jacket as a rain jacket. I have written a previous review, and I bought a 2nd one of these after I lost the first one. Last week while hiking in Finland, I lost the 2nd one. One of the things I loved about this jacket is that it stores inside a small pocket, and it has a loop that you can hook a D-ring through and hook it to a belt loop, or a harness point on a backpack. Thats where I had it last week, connected to my backpack, when the nylon in the loop gave way and the jacket fell too far down the side of the trail for me to be able to go get it. $130 down the drain. Maybe some other lucky hiker will find it. I may buy an other, but I will not count on that loop to hold out. I did get 2 years of good use out of it, but I wish it had not broken

This is the ideal ultralight jacket, providing plenty of protection from the elements without adding a lot of weight. It packs down incredibly small, so you will have no excuse not to bring it along on your next adventure.

I've had this jacket for about a year now and it certainly keeps me dry. It's very lightweight and has held up to some pretty good abuse. The waterproofing isn't the best straight out of the bag, so I've had to maintain its waterproofing a little more than I had imagined. It also doesn't feel to breathable, but I don't think I've ever had a rain shell that does. Super sweet jacket and I would totally buy it again.

I don't know what more I can add to the rave reviews. If you're ordering this jacket you want to go light and have done your research.

It lives up to the hype and checks all the boxes: ultralight, takes up minimal pack space, keeps you dry from rain, fits very well and is actually pretty stylish for a rain jacket.

I'm always on the fence between ordering a Med or Large for backpacking. 42" chest and want a slim fit but also the option of wearing over a fleece in colder weather. The Med is perfect for me. Fleece works great but a puffy would be pushing it.

Highly recommended.

This jacket is simple. It’s as light as you can imagine and it does its job. That’s what matters. It packs up into a tiny little ball that I never have to hesitate to throw in my day pack or even in my running vest. It’s waterproof enough too that I have full trust in it for multi-day excursions too.

This jacket does exactly what it was designed to do: Keeps you dry during those unexpected downpours, packs down incredibly small and weighs next to nothing.

My experience with the Helium II has largely been as a "just in case" piece while rock climbing and hiking when the weather is iffy. This jacket packs up quickly inside its stow pocket to about the size of a baseball - I have found the pocket is big enough to hold the jacket as well as a small snack and still be compact and light enough to forget about while clipped to my harness or tucked away in my backpack top pocket.

Considering the thin 30D Pertex Shield fabric is almost transparent, I was a bit worried about durability issues when I first got my hands on the jacket. But, after a trip alpine climbing in Canada's Northwest Territories my skepticism diminished; I ended up wearing the Helium almost continuously during my trip including two separate (20+ hour) big wall climbs in which we climbed loads of squeeze chimneys (hood fits nicely over my helmet!): Not one hole and the jacket was quite comfortable whilst climbing and hiking between tormenting cloudbursts!

I would not necessarily suggest this jacket for use if you will be inundated by wet weather for days on end, that said, I have used this it as a standalone piece for backcountry use in remote and wet locations with the knowledge that it does not have the best breathability like other, more robust Outdoor Research jackets - It does however dry fast!

I wear a men's Large and have a good bit of room for light layering: I'm 5.9, 175lbs, with a 41-inch chest.

Really solid for the price, I'd recommend having one of these in your pack at all times. It's so light and packable it won't make much difference, until the storm comes when it's a life saver.

I used it biking and hiking around Salt Lake in April. Great for those afternoon thunderstorms.

Such a great jacket to add to the bag for fighting strong wind and rainfall for those times you are not expecting it . Lightweight, pack-able, durable.

Email me with all your Outdoor Research questions - jelam@backcountry.com



The Helium is the type of jacket you'll want to add to your quiver of gear for times when you have no idea what the weather will throw at you. I busted out the Helium while I was exploring Zion when the rain hit and it was perfect for an emergency layer. I wouldn't use it for extended storms (get a 3-layer GTX for that) but the Helium kept me dry for 2-3hrs easy. The Helium is also light enough to be a layer that you never take out of your adventure pack. Even with no rain on the forecast, I've been happy to bring the Helium along as a wind layer, keeping me warm on high altitude peaks.