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Arc’Teryx Fission Belay Parka REVIEW

Product performance review of the Arc'Teryx Fission Belay Parka, a lightweight synthetic insulated backpacking jacket with a Gore Dryloft shell.


by Don Wilson | 2005-02-22 03:00:00-07


Arc'Teryx Fission Belay Parka - 1

Don over warm in his Arc'Teryx Fission Belay Parka with a climbing helmet under the hood to demonstrate the generous cut of this XL sized parka on his tall frame.

The Arc'Teryx Fission Belay Parka has both a waterproof/breathable shell and high loft synthetic insulation, features unique among the jackets in our review suite (although the MEC Magma Jacket is close to waterproof with its Gore Dryloft shell). This combination provides outstanding storm protection and significant warmth. The Arc'Teryx Fission Belay Parka is designed for climbing in difficult conditions and its hood and fit are well suited to keeping you warm and dry in alpine conditions. It includes typical Arc'Teryx features such as watertight zippers, a functional and highly adjustable hood, and superb quality construction. This combination of features and quality also carries a high price tag at a suggested retail price of $475.

In Brief

  • Waterproof/breathable Gore-Tex shell combined with PrimaLoft Sport insulation
  • Helmet friendly, adjustable hood
  • Watertight zippers
  • Generous cut for layering and covering your extremities
  • High quality construction throughout
  • Pricey at $475


• Garment Style

Full zip, high-loft, synthetic hooded belay jacket

• Fabric Description

270NR two-layer Gore-Tex XCR. The liner is 100% ripstop nylon 1.95 oz/yd2 (66 g/m2)

• Insulation Description

5.9 oz/yd2 (200 g/m2) PrimaLoft Sport

• Other Features

Vertical zip chest pocket, watertight zippers, hem drawcord, stuff sack

• Weight

2 lb 2.0 oz (964 g) as measured men's XL; 1 lb 12.4 oz (805 g) manufacturer specification men's M

• Loft

1.0 in (2.3 cm) single layer loft

• Model Year

Fall 2003


$475.00 Manufacturer's suggested retail price


Arc'Teryx Fission Belay Parka - 2
The angled cut on the hem of the Fission Belay Parka provides good coverage of the seat.

PrimaLoft Sport insulation is a blend of ultra-fine multi-diameter fibers that are specially treated and water resistant. The insulation has a warmth-to-weight ratio of 0.74 clo/oz and retains greater than 85% of its loft and warmth when wet due to its low water absorbency. (See Commentary on Sleeping Bag Rating Specifications for an explanation of the insulation unit "clo.") The Fission has this insulation in the arms and hood as well as the body. I measured the single-layer loft as 1.0 inch.

The Fission has a full front zipper that covers the mouth region when fully zipped up. The fixed diameter knit cuffs are not adjustable but are comfortable and keep the wrists fairly well sealed. The hood is highly adjustable and can cover almost the entire face when needed, either with or without a climbing helmet. There is an adjustable drawcord in the bottom hem. The back of the jacket has a slight drop that comfortably covers the rear end. I used the jacket at temperatures down to just below freezing. I was very warm in all of my tests with only light insulation beneath the jacket, even when not moving in freezing rain and snow. It is generously cut so that it can be donned over other clothing at belays or when your activity level drops. I also used the jacket in a bivy sack on a 25 °F night with a 40 °F rated sleeping bag. I slept warm and comfortable all night. I appreciated the generous cut of the Fission as a sleeping garment; it was not constricting yet kept my hips covered all night.

Storm resistance

As the only jacket in our review suite offering a Gore-Tex waterproof shell combined with high loft insulation, it is no surprise that the Fission Belay Parka offers excellent storm resistance. I tested the Fission in a variety of late spring mountain conditions. Even so, I was not able to test the jacket to the limits of its storm resistance capability. I stayed completely dry and warm at 9,400 feet during a spring storm after exposure to several hours of freezing rain. The jacket easily repelled this storm and kept my face totally dry while hiking and scrambling. Arc'Teryx is noted for watertight zipper technology and molded zipper garages. I put these to the garden hose test to far exceed the water volume of any storm conditions you are likely to encounter. After a full 10 minutes of drenching with the hose, including continuous flexing of the zippers under the water stream, not a drop of water had entered at any point on the jacket. The highly adjustable hood leaves only the eyes exposed when fully closed, and the stiff hood brim gives good protection from rain and snow. The waterproof/breathable shell does reduce the jacket's breathability relative to other garments in our review suite, but I did not experience significant problems with moisture buildup during my testing.


The Fission has a roomy cut and excellent articulation. I'm 6'4" and my size XL sample easily covers my rear and layers over multiple layers. I could possibly even get by with a smaller size, saving a few ounces. The Fission evidences quality construction throughout and proved quite durable in my testing, with no signs of wear. A stuff sack is included with the parka.


With a manufacturer's suggested retail price of $475, the Arc'Teryx Fission Belay Parka is not for everyone. It is designed for serious winter conditions with a waterproof Gore-Tex shell and high loft insulation. When you consider that the Fission can replace both your primary insulating garment and your waterproof storm shell - at significantly less weight - and also consider the quality of the garment, the cost seems more reasonable.

Recommendations for Improvement

Although the Fission is primarily designed for serious alpine conditions, it will get plenty of use around camp. Hand warmer pockets would make the jacket more comfortable to use in more sedentary situations. In alpine conditions, this jacket will get exposed to rock, ice, and climbing tools - highly abrasive situations not faced by most lightweight gear. Reinforced elbows and wrists would enhance the durability of the jacket.


"Arc’Teryx Fission Belay Parka REVIEW," by Don Wilson. (ISSN 1537-0364)., 2005-02-22 03:00:00-07.