Portwest Men's Polycotton Thermal Briefs B121

Portwest Men's Polycotton Thermal Briefs B121
Portwest Men's Polycotton Thermal Briefs B121
Portwest Men's Polycotton Thermal Briefs B121
Portwest Men's Polycotton Thermal Briefs B121
Portwest Men's Polycotton Thermal Briefs B121
Portwest Men's Polycotton Thermal Briefs B121
PWB121
In stock: Ships within 48 hours
€15.90 TTC
Select colors
  • White
  • Bleu marine
  • Black
SELECT YOUR SIZE
  • S
  • M
  • L
  • XL
  • 2XL
  • 3XL

Quantity Discount You Save
2 8% Up to €2.54
3 12% Up to €5.72
5 15% Up to €11.93
10 18% Up to €28.62
25 21% Up to €83.48
50 24% Up to €190.80
100 27% Up to €429.30
 

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SUMMARY

Create a layer of warmth around the lower body. 

The soft poly cotton fibres and fabric knitting mean that heat is trapped in.
Cuffed hem and elasticated waist provide a comfortable fit.

TECHNICAL DESCRIPTION

Men's Thermal Long Johns Portwest B121

LayerBase Layer
Fabric50% poly · 50% cotton
ComfortDown to −20 °C
SizesS to 3XL
PortwestReliable performance for everyday cold
Cold zone

Grand-Froid scale — temperature benchmark to compare models against each other:

COLD10 °C → −15 °C
HARD COLD−20 °C → −30 °C
EXTREME COLD−30 °C and below

The dependable thermal base layer for your legs — breathable polycotton, elasticated waist

The Portwest B121 Men's Thermal Long Johns are the ideal base layer to keep legs warm and skin dry in cold conditions. 50/50 polycotton fabric, breathable fibres, elasticated waist, fly opening, ankle hems, flat non-irritating seams. Protection down to −20 °C. Sizes S to 3XL in white, navy and black.

Expert opinion from Grand-Froid

The trouser half of the B123 — same fabric, same reliability. Solid, breathable polycotton, ideal under work or ski trousers.

Portwest B121 men's polycotton thermal long johns
What is it designed for?
  • Base layer under work, ski or hiking trousers
  • Construction, logistics, agriculture in cold conditions
  • Winter sports and extended outdoor activities
  • Daily commuting in cold weather
  • Indoor comfort in poorly heated spaces
Technical specifications
  • Thermal protection down to −20 °C
  • Breathable fibres: dry skin all day
  • Elasticated waist: comfortable fit
  • Fly opening
  • Ankle hems
  • Flat seams: non-irritating
  • Machine washable
Composition
  • 50% polyester — durability, quick-drying
  • 50% cotton — soft against skin, breathable
Size guide

These long johns fit true to size. Measure your waist.

MeasurementsSMLXL2XL3XL
Waist (cm) 76–84 84–92 92–100 100–108 108–116 116–124

Tolerance ± 2 cm.

Care & Durability
  • Washing: machine wash at 40 °C
  • Drying: tumble dry on a low/gentle cycle
  • Avoid: bleach, fabric softener, direct ironing
Why choose this model
  • 50/50 polycotton: cotton softness, polyester durability
  • Elasticated waist + ankle hems: stays in place under trousers
  • Flat seams: no irritation, even worn all day
  • Hard Cold zone −20 °C: for work and extended winter outings
The 3-layer system
Layer 1 — this base layer. Next to the skin: captures warmth, wicks moisture outward.
Layer 2 — insulation. Fleece or down: traps the warm air produced by the body.
Layer 3 — protection. Windproof or waterproof jacket: blocks wind and weather.

An effective base layer is close-fitting: that's what enables thermal capture and moisture wicking.

Returns & exchanges — 30 days
You have 30 days from receipt to request a return or exchange.

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