With a weight of 350g Bergans' Helium jacket does a pretty good job of living up to its name; it also has a low packing volume meaning you can stuff it in your backpack and forget about it until needed.
Build quality is also good and sturdy for a lightweight jacket, with the 2 ½ -layer Dermizax fabric having the feel that it will handle plenty of stick.
The Helium is waterproof, windproof and breathable and has fully-taped seams to ensure even the heaviest of rain is kept on the outside, and there's plenty of room for layering underneath it in cooler conditions; our 'Large'-size tester had stacks of room inside it and if anything found it slightly too big, so you may need to think about dropping down a size.
For a lightweight jacket the Helium has plenty of useful features. The fixed hood has wire reinforcements on the peak and can be easily adjusted to give a superb fit and excellent peripheral vision.
In addition there are two map-compatible, zipped mesh hand pockets which allow for extra breathability/venting, pit zips, ergonomically cut, Velcro-adjustable cuffs and an extended back.
In conclusion, the Helium wasn't the lightest jacket we tested, but it's certainly a great all-rounder in terms of features, performance and cost and is well worth checking out.