JMT Jacket

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Minimalist 2 season synthetic insulated jacket for light layering. At 7 ounces for a size medium the hooded JMT packs tremendous warmth and function in a small, all conditions package. 

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The JMT Jacket is our lightest insulated shell. Designed for summer layering in the mountains, it's named after the classic John Muir Trail in the Sierra. View it as an insulated windbreaker.

Built with Climashield APEX, a lightweight yet remarkably efficient synthetic insulator, the JMT Jacket will retain some warmth when damp, and will dry and recover more quickly than down. 


The JMT Jacket is trim and devoid of clumsy features. It is best applied as a warming layer over one or two thin thermal shirts, either on the move or during brief recovery stops.

Additionally, the JMT can be put to use as extra core insulation while sleeping, thus making a lighter sleep system possible.


This is a simple jacket, lean on features, with the focus on as much warmth for the weight as possible. In its basic configuration the APEX insulation makes up over 55% of the total weight.

We make it with or without an integrated hood. The hood option is fully insulated and offers complete coverage including above the chin - but is not helmet compatible. In fact, for most users, only a very thin beanie will fit under this trim hood.

The chart below reflects the JMT with a hood. Choosing a collar will save 20-25g depending on size.

The standard front closure is a YKK #3 full length coil zipper. With a little care such a thin zipper can last the life of at least the insulation.

For a weight penalty of 13-16g we do include an option for a much more durable #5 YKK Vislon zipper. 

We make the JMT Jacket without any exterior pockets. For now these are not available on a custom basis either. Interior pockets can be configured on the menu, placed either left or right at chest level plus two lower drop-in cargo pockets. Adds about 7g each.

The hood casing and waist hem have fixed, pre-tensioned shockcords. The sleeve ends are cut trim with no additional closure offered.

Synthetic Fill

APEX by Climashield, a superior continuous filament synthetic insulation, is the choice here.

For the JMT Jacket we use 2.2oz/yd - 75g/m Climashield APEX which is light, compact, and applicable for 2, maybe 3 season use. With minimal sewn through stitch lines (virtually none on the shell), and substantial loft in the APEX, the JMT is surprisingly warm and, likely more important, not subject to shifting down leaving cold spots, as well as very resistant to moisture from sweat and weather.  


The JMT Jacket can be configured with a 10d taffeta* in a number of different colors. It's an ultralight fabric for folks who want the lightest, but realize that abrasion and tear resistance is minimal.

Also available is a 7d ripstop** with advanced weatherproofing qualities.

At this point we can offer more durable fabrics on a special order basis only. These include Epic and multi-cam. Please email or call.

*Membrane. Our 10D taffeta. Smooth, comfortable and about the lightest material possible for practical shell use, at 0.66 oz/yd. Very breathable with minimal moisture repellency. Also the standard inside liner. Black, Moroccan Blue, Burnt Orange, Coyote Brown and Royal Purple.

**Robic Ripstop. A special material based on an ultralight, yet relatively durable 7D base fabric with a breathable micro porous coating. The 0.74 oz/yd Robic excels at shedding mist and light rain. A so-called waterproof/breathable fabric, this high tech shell sports a HH (hydrostatic head) of 1000mm, while providing enough vapor transfer for mild activities (good breathability). Color is medium grey.


The chart below outlines the many options for sizing the JMT Jacket. The cut is generally aimed at providing a trim fit, best when used over only one or two lightweight thermal layers. Compared to the Skaha line of down and APEX hoodies, the JMT Jacket is roughly a fulll size smaller (L > M) in torso and sleeve circumference, while body and sleeve length are comparable. 

The size small use a 24" zipper. If you're a tall size small (5' 8"+) consider added length with a 26" zipper. Contact us regarding this.

The menu offers a choice of adding 2" or 4" to the lower back length, while the front remains unchanged.

One can also add 2" to the sleeve length. 

Also see here.

Colors pictured: Moroccan Blue with Burnt Orange liner, and Black with Coyote Brown liner.



The jacket arrived today.

First impressions are: WOW!

It fits me perfectly. I'm pleased I went for the longer back length and longer sleeves.

The material feels great and the jacket feels warm.

The #5 two way zip is superb - I've never been a fan of lightweight zips. The extra weight for it is so minimal.

The total weight is amazing - 239 grms!

Many thanks for such a superb piece of gear!

Best wishes,

G in the UK



    I am very impressed with the JMT jacket I must say.
    no frills, all function, truly UL.

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      JMT Jacket

      JMT Jacket

      Minimalist 2 season synthetic insulated jacket for light layering. At 7 ounces for a size medium the hooded JMT packs tremendous warmth and function in a small, all conditions package. 

      Product Options
      Torso Length
      Adds a number of inches to the back and front length of the selected general size.
      Sleeve Length
      For folks with long arms, or skinny torsos.
      Shell Fabric

      Please see our Fabric Page for help choosing the right shell material

      Liner Fabric
      Membrane for ultralight priority, or bright orange Pertex Quantum for safety visibility when inside out.
      Integrated Hood and Collar Choices
      Choose how to finish out the head opening. Getting an integrated hood eliminates all collars.
      Interior Zippered Chest Pocket
      With a vertical opening hidden behind the main front zipper, these pockets are protected yet easily accessed.
      If choosing just one consider a left side pocket for right-handers and vice-versa.
      Each pocket adds 8 grams in size large.
      Lower Drop-in Cargo Pockets
      These are large interior pockets with a plain top opening for bulky items. Not suitable for valuables or heavy loads.
      Zipper Size
      The #5 zipper adds 15 grams to the jacket.