The world's most in-depth and scientific reviews of outdoor gear

Outdoor Research Helium II - Women's Review

The lightest weight and most packable jacket tested, this earned a Top Pick.
Top Pick Award
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Price:  $159 List | $89.58 at Amazon
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Pros:  Lightest rain jacket tested, most packable rain jacket tested
Cons:  Not waterproof, not very durable
Manufacturer:   Outdoor Research
By Holly Zynda ⋅ Review Editor  ⋅  May 4, 2018
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#9 of 10
  • Water Resistance - 30% 2
  • Breathability - 15% 9
  • Comfort - 20% 9
  • Weight - 15% 10
  • Durability - 15% 6
  • Packed Size - 5% 10

The Skinny

Outdoor Research's Helium II stood out as the most lightweight, compact jacket among those we tested this year, earning a perfect 10 and far outranking all of the competition in both packed size and weight. It performed so well in these categories that we chose it as our Top Pick ultralight rain shell. This jacket serves as both a wind shirt and a light rain shell for the minimalist outdoor enthusiast. Performing well as both a just-in-case measure in the bottom of your bag or as an added layer for the ultralight adventurer, this well-constructed and durable jacket gives you protection for very little bulk invested. However, what it provides in light weight and compactness, it sacrifices in water resistance, so it may not be advisable to use this jacket if you plan on facing extreme weather conditions with wind and rain or cold weather.

New Colors Available
The Helium II is now available in a variety of new color options, but the design of the jacket remains the same since we last tested it.

Compare to Similar Products

Our Analysis and Test Results

Performance Comparison

At half the weight and half the packed size of the next closest lightweight jackets, the Outdoor Research Helium II was hands-down the lightest of the rain shells we tested, measuring only a third of the size and weight of the bulkiest of the jackets. To maintain its minimal dimensions, this jacket disregards many of the bells and whistles of the more complex jacket designs, giving you only what you need to stay protected from the weather and comfortable while on the move. With its Pertex Shield®+ ripstop fabric, you get extreme breathability and a bit of added durability in a small package.

Testing out the Helium II in real conditions just as a storm rolled in South Lake Tahoe.
Testing out the Helium II in real conditions just as a storm rolled in South Lake Tahoe.

Water Resistance

The Helium II uses Pertex® Shield+ nylon fabric with a PU film laminate, which offers a great waterproof rating, but while it boasts superior protection, we did not find that it lived up to the hype. What you gain in lightness, you lose in water protection. When tested in torrential downpours and high-pressure spray, the fabric wet like a standard non-waterproof layer. This lack of performance makes this a better jacket for wearing in light rain, mist, or fog or for a bit of extra wind protection, so if you are planning on heading out in a heavy downpour, you may want to pick a different jacket. Nevertheless, it had a number of advanced features for added water resistance, like a crown cincher to keep your hood in place, even in the wind or when moving around, and a stiff visor on the hood to keep rain off your face.


The Pertex® Shield+ nylon material with a PU film laminate of the Helium II helped this shell rank highest in breathability, beating out much of the competition. While this jacket doesn't offer features like pit zips or a mesh liner, it doesn't need those, as the fabric is thin and air-permeable enough to keep you cool, even during extreme exertion. However, on the flip side, it certainly won't keep you warm on a wintery day, and doesn't serve as a highly effective wind breaker, but if you plan on just using this as a shell over layers to keep mist or light rain off, it will add an extra layer to keep you warm.


Perfect as an outer garment over base layers, this jacket ranks highly in comfort. The Helium II's extremely lightweight, soft, pliable, and smooth material proves comfortable for wearing for a hike on a warm day with a t-shirt or wearing while cross-country skiing over an insulating underlayer. And, with its minimal design, there are few opportunities for chafing or rubbing. The designers even added little bonus features, like a protective flap on the inside of the top of the zipper to keep your chin comfortable when zipped all the way up. However, one of the drawbacks is no standard pockets in which to put your hands, so remember to bring gloves if wearing this in cold weather. Moreover, if you plan on moving around a lot in this jacket, it may not stay in place, but it will move with you, allowing a full range of motion but riding up if you plan on wearing it with a backpack while climbing.

When the weather is variable  you want to rest assured that your rain jacket will both keep you dry and keep you cool while out on the trail.
When the weather is variable, you want to rest assured that your rain jacket will both keep you dry and keep you cool while out on the trail.


We don't often give jackets a perfect 10 ranking, but the Helium II blew the competition out of the water, coming in at only 5.82 ounces. The designers at Outdoor Research focused entirely on light weight when making this jacket, unfortunately sacrificing water and wind resistance. However, its lightness makes it perfect for long backpacking trips and for throwing in the bottom of your bag just in case you might need it. In fact, with its stuff sack, mentioned later, you can even clip it to your belt when traveling very light.

The Outdoor Research Helium II was  by far  the most compact and lightweight shell of those we tested  making it a great ultralight option.
The Outdoor Research Helium II was, by far, the most compact and lightweight shell of those we tested, making it a great ultralight option.


Not the most rugged of the jackets we tested, the Helium II sacrifices durability in order to make it more appealing to take with you everywhere with its light weight and small size. The thinness of the material is balanced by ripstop fabric, so even if you do get a snag, it shouldn't grow. However, if you do take this jacket on all of your outdoor adventures, you may want to plan on replacing it in the future, as it may not stand up to a ton of heavy use.

Packed Size

When packed in its handy-dandy stuff sack pocket with carabiner loop, this jacket measures a mere 4.5x4.5x3 inches (60.75 cubic inches), making this the most compact jacket we tested. This earned it a second rare 10-point rating, securing its place firmly as the best ultralight rain jacket. When tucked away in its stuff pocket, you can easily clip this shell to your belt loop for easy access or toss it in your backpack for later use.

Offering extreme portability  the Helium II packs down into a handy-dandy pocket stuff sack.
Offering extreme portability, the Helium II packs down into a handy-dandy pocket stuff sack.

Best Application

The Helium II stands as the leader in lightweight athleticism, hitting a perfect 10 in both weight and packed size. Whether you are hiking, kayaking, camping, fishing, climbing, or pursuing any other outdoor activity, this shell is the perfect piece of equipment for the serious lightweight athlete or as an added layer for anyone else. It will provide a layer of light wind and water protection over layers or just something to keep the sun off when wearing a tank or T-shirt.


At $159, this jacket offers a fairly good value for a lightweight rain shell. For anyone that doesn't care about bulk or weight, it is less of a value, since it trades this for water and wind protection. However, if you are an ultralight adventurer, you may not be able to find a better rain shell for your needs for the price.


We tested the Helium II from the tops of the Sierras down to Lake Powell to rank its performance against the competition.
We tested the Helium II from the tops of the Sierras down to Lake Powell to rank its performance against the competition.

Getting a rare perfect 10 in both weight and packed size, the Helium II won our Top Pick as the best ultralight rain jacket we tested. When heading out into unpredictable weather or considering an added layer when backpacking into deep backcountry or over a mountain peak, this jacket will serve as an ideal minimalist shell.

Holly Zynda