Weatherproofness
Wind-wise, the Second Light holds up great, fending off gusts and offering pleasant warmth on those cool, early-A.M. runs. Although it’s supposedly “highly water resistant” with a light PU coating and DWR, we found it to wet out almost immediately in even light rain. The sleeves quickly grew clingy and cold.

Breathability
This jacket offers a pretty standard level of breathability—not bad for your average, low-intensity run, but nothing outstanding either. Lacking any designated back or underarm venting, it trapped internal heat a bit more than other jackets in this review.

Function
We especially appreciated the thumbholes in this jacket, integrated almost invisibly, which help keep the sleeves in place in high wind. The rear zip pocket can secure small essentials on your run, and it doubles as a convenient stuff sack for when you want to pack the Second Light away. The fabric itself is a high-quality ripstop nylon that holds up well to abrasion and snags.

Fit/Comfort
Nothing but raves here: the fabric is easily the comfiest of any we tested this round, offering ample stretch and, accordingly, terrific range of motion. It fits relatively true to size, with some style-focused design touches—ruching at the shoulders, a tall collar, and a nice drop hem in the back for solid coverage.

Packability
At 3.49 ounces, the Second Light fits right in line in this category—exceptionally light, and easily scrunched up into its own zippered pocket for quick stowing.