Polycotton Thermal Long Johns, Base Layer

Men's Very Cold Thermal Long Johns Portwest B121

1 pièce	2	3 à 4	5 à 9	10 à 24	25 à 49	50 à 99	100 et +
15,90 €	14,63 €	13,99 €	13,52 €	13,04 €	12,56 €	12,08 €	11,61 €

SUMMARY

The Portwest B121 thermal long johns are a base layer in polycotton to wear next to the skin, under work trousers: elasticated waist and rib-knit ankles keep them in place. They slip under work clothes and are soon forgotten, with a soft knit and a comfortable fit. Pair them with the B123 thermal top for a complete set. Sizes XS to 6XL.

TECHNICAL DESCRIPTION

Polycotton Thermal Long Johns Men — Portwest

PROTECTION Very Cold

MATERIAL Polycotton 50/50

USE Professional

THERMAL PROTECTION Down to −20 °C* / −4 °F

Fit Elasticated waist and ankles

The base layer for the legs: it slips under your work clothes and you forget it

The B121 thermal long johns create a layer of warmth around the legs. Their soft polycotton knit stays pleasant on the skin, and the elasticated waist and rib-knit ankles keep them in place under work trousers.

They are worn next to the skin: an extra layer in between blocks moisture from escaping and cancels the thermal effect.

They are the lower body's first layer, to pair with the B123 thermal top. Sizes XS to 6XL.

Grand-Froid expert's view

The right move is to put them on in the morning before you dress, not over underwear: contact with the skin makes all the difference. The rib-knit ankles stay under the sock without rolling. For the top half, pair them with the Portwest B123 thermal top. A base layer only warms you if it touches the skin.

thermal long johns men Portwest B121 - very cold −20 °C / −4 °F

What is it designed for?

A base layer for legs exposed to the cold, at work and outdoors.

Cold work under work clothes: a layer close to the skin under your trousers
Construction and outdoor work in winter: legs protected under work trousers
Long standing jobs outdoors: legs still, cold rising from the ground
Travel and waiting in cold weather: slips under ordinary trousers
Complete them with the Portwest B123 thermal top for a full base layer set, from top to bottom

Thermal protection

The knit holds warm air against the leg, under work trousers or bib overalls. Under a fleece and a parka, it completes the layering system for days of moderate effort. Cotton retains moisture: for sustained effort that makes you sweat, choose a merino wool or synthetic base layer.

Technical specifications

Elasticated waist
Elasticated ankles — rib-knit hem
Fit — comfortable

Composition

Knit — 50 % polyester, 50 % cotton, 200 g/m²

Commitments

EN 14058 — protective clothing against cool environments: class 2, thermal resistance 0.137 m²·K/W
CE conformity

Size guide

Measure your waist at navel level, without pulling tight. Between two sizes, take the larger one to stay comfortable under work trousers.

Size	Waist (cm)	FR size
XS	68–72	34–36
S	76–80	38–40
M	84–88	42–44
L	92–96	46–48
XL	100–104	50–52
2XL	108–112	54
3XL	116–120	56
4XL	124–128	58
5XL	132–140	60
6XL	144–152	62–64

Body measurements in cm.

Care & Durability

Washing: machine wash at 40 °C / 104 °F maximum, gentle cycle
Bleaching: avoid
Drying: air dry on a line, no tumble dryer
Ironing: 150 °C / 302 °F maximum

Return or exchange — 30 days

You have 30 days after receipt to request a return or exchange for this item.

Why choose the Portwest B121 thermal long johns?

The base layer for the legs: a soft polycotton knit, elasticated at the waist and ankles, that slips under work clothes.

The three-layer system:

1st layer — base (role of this product): next to the skin. Captures body heat and moves perspiration outwards.
2nd layer — mid layer: insulates and holds warm air around the body. Fleece, knit or thermal top.
3rd layer — outer: shell, softshell jacket or padded gilet. Blocks wind and holds warmth. In sustained rain, a hardshell takes over.

For a complete base layer, pair these long johns with the Portwest B123 thermal top: matching top and bottom.

* Indicative temperature. Perceived warmth varies with activity, body type, humidity, wind and the layers worn underneath.