Online Firewall Mountain 3L Pants Waterproof Overtrousers

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Tough, streamlined, and built for serious weather, these trousers are ideal for big mountain days when performance matters more than weight.

Rab says: 

Designed to accompany you on all-mountain hikes, scrambles, and ascents, these versatile waterproof pants take up minimal space in your pack, yet provide dependable protection in any conditions. They’re engineered with 3-layer Pertex® Shield, deflecting hammering rain to keep you bone dry and making smooth progress towards the summit. With a part-elasticated waistband and full-length side zips, they’re quick to pull on over boots and crampons so there’s no delay when a storm is closing in.

Our Verdict

The Rab Firewall Mountain 3L Pants are an impressive combination of protection, function, and fit. At 355g for a Medium, they’re light for a full-spec shell trouser, and the 3-layer Pertex Shield fabric feels durable and breathable. The full-length side zips use triple pullers, meaning they can get over boots and help with ventilation during climbs.

The cut is generous enough to layer over baselayers or trousers, but not baggy. Articulated knees and a long gusset make movement feel unhindered on steeper ground. I found the waistband comfortable and stable under a pack, though the absence of pockets does limit quick-access storage.

– Reviewed by Ultralight Outdoor Gear

Features

• Lightweight, part elasticated waistband reduces bulk while providing support and structure
• Long length gusset at crotch and knee articulation for ease of movement
• Full length 2-way YKK® AquaGuard® side zips with internal storm guard and triple pullers
• Drawcord adjustable hem to accommodate different footwear

Specifications

• Small weighs: 344g
• Medium weighs: 355g
• Large weighs: 374g
• XLarge weighs: 383g
• Fit: Regular

Material & Construction

• 40D Pertex® Shield 3-Layer construction waterproof technology with fluorocarbon-free DWR (133gsm) HH: 20,000mm/MVTR: 20,000 g/m2/24hrs
• Main Body: 100% Polyamide (Recycled) with Polyurethane membrane, Reverse: 100% Polyamide

Help & advice:

• Pertex Shield Technology Explained
• About Rab
• Choosing a Waterproof Jacket
• MVTR Breathability
• Hydrostatic Head
• Rab Sustainability and Responsibility