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MontBell U.L. Down Inner Jacket REVIEW

The lightest down jacket on the market.


by Carol Crooker | 2005-12-13 03:00:00-07

MontBell U.L. Down Inner Jacket REVIEW


The MontBell U.L. Down Inner jacket is the lightest down jacket on the market. MontBell has kept the design simple and materials lightweight to create a full front closure down jacket weighing less than 7 ounces in size medium.

What's Good

  • Very light weight
  • Shell fabric has minimal down leakage and is water resistant
  • Good fit - sleeves and torso are long enough, the collar is not too tight
  • Dropped tail adds a couple of extra inches of rear coverage
  • Silky smooth inner and outer fabric makes layering easy

What's Not So Good

  • Snap front closure has gaps that let wind in - it is best suited as a mid layer, as it is designed to be used
  • Underweight - our sample weighs 0.8 ounces less than specified


Model Year



Full front snap closure jacket


Size men's M tested. 6.6 oz (187 g) measured weight, manufacturer's specification 7.4 oz (210 g)

Shell Fabric

Down specific 15d Ballistic Airlight hollow fiber nylon shell


1.6 in (4.1 cm) double layered, measured


2.1 oz (60 g) of 725 fill power hypoallergenic goose down


Single-quilt construction, snap closure, elastic cuffs, DWR treatment



* Loft is a weighted average of maximum double layer lofts in the torso and sleeves. Torso loft is double weighted.


I tested the MontBell U.L Down Inner jacket in a variety of conditions: desert high country in the fall and spring, southwest canyon country in the spring, and the Oregon dunes in early summer. Temperatures were moderate and rain was mild. The jacket hits the design mark of a very lightweight, warm layering piece. At around 7 ounces, it's easy to justify throwing it in the pack for a little extra around-camp, and bag rating boosting warmth.

Features are kept to a minimum with a snap front closure, non-adjusting elastic cuffs, and a drop tail - no pockets. The design is carefully thought out. Sewn through baffles vary in size and shape so that the jacket fits the body. The stand up collar, an area that could have easily been neglected, thoughtfully has two baffles and two snaps to keep collar and down in place and your neck warm. Articulation is fair; the bottom hem lifts about an inch when arms are raised parallel to the ground, and 3 inches when arms are raised overhead - but the U.L. Down Inner is long enough to prevent a breezy gap between pants waist band and jacket bottom even when reaching overhead.

The shell fabric is 15-denier Ballistic Airlight nylon, which MontBell claims is more abrasion resistant and has a higher tear strength than other similar weight nylon fabrics. The Ballistic nylon is created by heating and stretching nylon fibers so that the nylon molecules in each fiber align and the fibers become stronger. I did not experience any damage to the shell fabric in the course of testing, even after a minor amount of bushwhacking. The tight weave of the fabric helps to keep prickly things from catching in the fabric. DWR and the tight weave kept the Ballistic nylon from wetting out even after 40 minutes in a light sprinkle.

Construction quality is good, with finished inside seams and even stitching. When I first saw the jacket, I was concerned about the durability of the small plastic snaps on the front closure. The snaps are attached to a strip of grosgrain ribbon, which adds a bit of stiffness and strength. I have not babied the snaps and none have pulled out or loosened during the test period.

Our medium sample MontBell U.L. Down Inner jacket weighs 0.8 ounces less than is specified for a size medium, and some of the baffles are a little flatter than others. This is one case where I'd prefer that an item not weigh less than specified. With that said, the U.L. Down Inner is warm and cozy and very light. It's the jacket I pack when I'm expecting lows of around 40 ºF.

What's Unique

The MontBell U.L Down Inner is the lightest down jacket on the market.

Recommendations for Improvement

MontBell's concept for the U.L. Down Inner series is to: "make the lightest and warmest insulation layer available." They've hit their mark. I miss a zipper at times, but it would add weight - unneeded weight since the jacket is nice and warm as a mid layer under a wind jacket - as it's intended to be used.


"MontBell U.L. Down Inner Jacket REVIEW," by Carol Crooker. (ISSN 1537-0364)., 2005-12-13 03:00:00-07.