This is one lightweight windproof. Hitting the scales at just 68g (large), the Helium is hardly there at all, yet the rip-stop nylon fabric keeps the breeze out well.
It’s also surprisingly water resistant if you get caught out in a shower, though the seams aren’t taped so you’ll need something more hardcore if the forecast is wet.
The cycle-specific cut is slim so there’s little flapping, with generous length at the rear to keep your lower back covered, while the sleeves are plenty long enough to cover your wrists and the cuffs are elasticated for effective sealing. We did find the raglan shoulders a little tight when we stretched down to the drops, though.
It has a zipped rear pocket large enough to hold all your ride gubbins. Small perforations on the sides and under the arms increase breathability while the asymmetric zip, which avoids any scratching under your chin, allows simple air conditioning.
If you do start getting hot, just whip the Helium off; it’ll pack to the size of an orange and fit easily into any jersey pocket.