We loved how the Helium II jacket could be stuffed into its inner pocket, a neat touch rarely seen on waterproof jackets. The little package you're left with is around the size of a Big Mac but pliable enough to tuck into the smallest slither of space in your backpack. The weight ain't half bad either, with the medium size barely tipping the scales at 174g. Those in the know will appreciate that this is a great weight for a waterproof jacket, making it a real contender for ultralight backpacking trips or for emergency rain protection on your travels.
As lightweight and packable as it is the Helium II jacket still needs to stop you getting wet in demanding conditions like carrying a heavy pack, up a steep hill, in a torrential downpour - and this is where some ultralight jackets fail miserably. Mercifully the arm and hem length are both just long enough to offer protection in a storm, and the hem can be cinched up easily using a single drawcord adjuster. The elasticated cuffs are comfortable and they stop trickles of water creeping up your arm, but they're difficult to pull over a pair of gloves due to their lack of adjustability.
The hood comes equipped with a volume reducer that works well, and a large, slightly stiffened but wireless brim which effectively keeps water off your face. You can flip the brim up for hiking or fold it inside if you want a more subtle look. The top of the jacket sits quite low on your chin which leaves a bit too much of your face exposed but it's comfortable nonetheless. The gram counters have clearly been at the material around the back of the neck and there's not quite enough of it for the hood to be fully unrestricted in use and it pulls slightly at the far extents of head movement. Having said that, the overall impression of the hood is positive considering the weight and pack size.
The 2.5-layer Pertex Shield+ material is a little stiff but manages to produce less crinkle and swish sounds than an equivalent Gore tex fabric, that's not scientific of course, just our anecdotal opinion. A 15,000mm hydrostatic head (waterproof rating) is lower than the more usual 20,000mm+ but, with taped seams and water-resistant zips it'll still be an awful long time before you get water seeping in - in reality it's probably nothing to worry about.
The 20,000 MVTR breathability rating is on par with other jackets at this price point, the Helium II feels pretty good in use but there are no pit zips or mesh pockets so dumping excess heat is taken care of exclusively via the main zip.
Layering isn't a problem with the Helium II, there's plenty of wiggle room inside and arm articulation is good without any dodgy tugging at the shoulders. Apart from the slightly clammy feeling you get with a 2.5 layer jacket the overall comfort is decent allowing you to wear the jacket for long periods without wanting to tear it off.
Face fabric is predictably thin at 30D but the Helium II still feels sufficiently tough and well made and not wafer thin and fragile like some.
Overall the Helium II successfully straddles the line between weight, functionality and performance and at £140 it's also good value for money. We recommend this jacket if you're in the market for something lightweight and packable that you can chuck in your pack and rely on to keep you dry in a storm.