All jackets give a waterproof and breathability rating. Waterproof rating is called Hydrostatic Head. Downpour Plus is Hydrostatic Head: 20,000 mm, Breathability: MVTR 20,000g/m2/24 hrs
https://www.snowandrock.com/expert-advi ... ained.html
Waterproofness Ratings:
5,000mm: This is the minimum rating for a jacket to be called rainproof, however, it won’t stand up to much more than a light shower.
10,000mm – 15,000mm: A jacket in this range will withstand most downpours as well as heavy snow, but will soak through over time if subjected to pressure, such as crashing in wet snow, kneeling or sitting down, or a heavy pack.
20,000mm and Up: This is the rating you should look for if you plan to be out in all conditions carrying a heavy load.
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Breathability Ratings:
5,000 – 10,000g/m²: This level of breathability is fine for resort skiing, urban travel or camping in the rain, but will get a bit clammy during high-intensity hiking or climbing.
10,000 – 15,000g/m²: Jackets in this range are suited to more adventurous travel or backcountry skiing, but breaking trail through snow or straight uphill might prove too much.
15,000 – 20,000g/m² & above: An extended trip to the hills, trekking in warm climates or otherwise working hard and perspiring heavily will require a jacket this breathable.
Also, all good jackets should have an adjuster toggle at the back of the hood to reduce the volume. The Flux don't have this, but they are aimed at cyclists. I put my helmet on top and no adjuster is needed or wanted. Look out for "Front and rear hood adjustment"