Weathershedding
This 2.5-layer waterproof shell with fully taped seams boasts outstanding rain protection. Testers took it out for several runs in afternoon rainstorms and never got wet. Velcro cuffs snug up the fit at the wrists to keep out rain, though not always as tightly as hoped.

Breathability
This jacket is designed with Mountain Hardwear’s proprietary Dry.Q Active technology, which was designed specifically for aerobic sports like running and works quite well. It doesn’t suffer from the same, typical levels of clamminess on the interior that many fully waterproof jackets do. The pit zips offer an extra breath of fresh air for charging up steep climbs in the rain. 

Function
The zippered hand pockets are quite roomy—plenty of space to stash gloves, a cap or other accessories on the go. The pockets are also mesh-lined providing additional vents for breathability. Two-way adjustment toggles cinch down the hood, so it stays in place even when the main, front zipper is partially unzipped. Even with the adjustments, testers did find the hood to ride a bit low over their eyes sometimes. 

Fit/Comfort
Wearing this material once will spoil you. With four-way stretch and an incredibly soft hand touch for a hard shell, the Stretch Ozonic feels unbelievably cozy. With unrestricted movement all the way through, the stretch fabric is particularly excellent while running—particularly on steep climbs, where you might be using trekking poles and thus needing more mobility through your shoulders.

Testers found the fit to be quite large, possibly to allow for layers underneath for backpackers. Runners might consider sizing down.

Packability
The pliable stretch fabric bunches up quite easily into a small package, though this jacket weighs on the heavier end of the scale of ultralight shells we tested.