The science of staying dry.

A waterproof shell is not magic — it is material science. Every jacket is built around a three-layer Hydroshell™ membrane engineered to keep water out, let vapor escape, and last for thousands of storm cycles.

28^{000 mm}

Hydrostatic Head

Three-layer membrane withstands a 28,000 mm water column — hurricane-grade waterproofing.

24^{k g/m²}

MVTR Breathability

Moisture vapor transfer keeps you dry from the inside during high-output ascents.

480^g

Shell Weight

Featherweight face fabric packs into its own chest pocket. Disappears in your pack.

100^k+

Flex Cycles

Articulated patterning tested through 100,000+ movement cycles without delamination.

Construction

Three layers. One shell.

Each layer has a job. Together they make a single material that sheds water, breathes, and survives.

Face Fabric

70D high-tenacity nylon ripstop with PFC-free DWR. Sheds abrasion, snow, and surface water.

Hydroshell™ Membrane

ePTFE membrane with 9 billion pores per cm². Blocks liquid water, passes water vapor.

Tricot Backer

Brushed polyester tricot protects the membrane and wicks moisture away from skin.

Principle 01

The three-layer laminate.

A waterproof shell is not a coating — it is an engineered stack. The face fabric sheds abrasion. The membrane stops water. The backer protects and wicks.

We laminate these three layers into a single sheet under heat and pressure. No delamination. No separation. One material that moves with you.

Principle 02

Where water meets resistance.

Hydrostatic head measures how much water pressure a fabric can resist before leaking. 28,000 mm is the equivalent of a 28-meter column of water pressed against one square centimeter.

Translation: hurricane rainfall, sustained for hours, will not penetrate a STORMFELL hardshell. The water beads, rolls, and falls away.

Principle 03

Breathable where it matters.

Waterproofing is meaningless if you drown in your own sweat. MVTR — Moisture Vapor Transmission Rate — measures how quickly perspiration escapes through the fabric.

Our membrane contains billions of microscopic pores. Each is 20,000 times smaller than a water drop, but 700 times larger than a vapor molecule. Water stays out. Sweat gets out.

Reference

The numbers, verified.

Independent lab results, not marketing claims. Every figure measured under ISO 811 (waterproofing) and ISO 11092 (breathability) protocols.

Membrane Hydroshell™ ePTFE, 9 billion pores/cm²

Waterproof 28,000 mm hydrostatic head (ISO 811)

Breathability 24,000 g/m²/24h MVTR (ISO 11092)

Face fabric 70D high-tenacity nylon ripstop

DWR PFC-free, C0 durable water repellent

Seam tape 13 mm micro-tape, fully sealed

Flex cycles 100,000+ (Bally flex test)

Waterproof warranty Lifetime on seams and membrane

Certification bluesign® · OEKO-TEX® Standard 100

Sustainability Bluesign-certified mills, recycled face fabric

See It In Action

Tested in the worst.

Field-tested by 200+ guides, runners, and rescue teams across six continents. The technology is only as good as the storms it survives.

See the Products Field-Test Story