MontBell’s Ultralight Thermawrap Action Jacket combines the loft and wind resistence of synthetic fill with the higher breathability of stretch fleece side panels to produce a jacket better suited to high octane pursuits. This is a close fitting jacket best suited to above freezing temperatures or layering under heavier insulation. I tested the 10.2 ounce (size M) MontBell Action Jacket while mountain biking, trail running, cross-country skiing, and backpacking through the colder months in northern Arizona (>7000 feet elevations).

This jacket received a major improvement in 2006. Previous versions of the Action Jacket used a YKK Conceal main front zipper (and actually included an instruction card on how to use them). Conceal zippers are aesthetically pleasing, as the zipper teeth disappear when zipped up. However, these zippers were difficult to operate, especially while wearing gloves, and were a source of complaints from users. Specifically, they are difficult to get started when trying to connect the two separating parts.

In 2006, the Conceal zippers were replaced with smooth-operating, standard YKK coil zippers. Having used both types, the new coil zippers are much appreciated. The two hand-warmer pockets still have Conceal zippers, but since these are permanently together (non-separating) they don’t have the same problem as the previous main zipper.

The Thermawrap Action Jacket uses 50 gram/m2 Exceloft insulation. In my experience, MontBell’s propriety Exceloft insulation performs similarly to Polarguard or Primaloft in jackets of similar loft. The Action jacket takes a fair amount of rain or snow before wetting through (partial thanks to the DWR coating), maintains warmth when wet, and dries quickly. The 15-denier Ballistic nylon shell material held up well to light abuse; no rips or snags after 8 months of use.

The MontBell Thermawrap Action Jacket is a trim fit (author is 5’7″ and 160 pounds, size medium tested). It layers well over a single long-sleeve base layer, and easily layers underneath additional layers of insulation or a trim rain jacket. The side stretch panels provide this trim fitting garment with plenty of stretch and freedom of movement. The stretch fleece enhanced breathability as well; they extend down the sleeves nearly to the elbows.