Helikon-Tex US Level 1 Thermal Layer — long-sleeve base layer shirt

The Helikon-Tex US Level 1 is a long-sleeve shirt in 100% polyester designed as the first layer in a layering system. Weighing 156 g, it is worn directly against the skin and manages moisture produced by physical activity, keeping the skin surface dry before heat is dispersed by the outer layers. It is suited to shooting in cold conditions, operational use in winter, and any outdoor activity where sweat trapped under heavy clothing becomes a thermal problem.

Technical polyester moves moisture away faster than cotton and does not retain it in the fibres: during a break after fast movement, the skin stays noticeably drier and the sensation of cold is reduced. This is not a waterproof fabric or a windproof membrane — its specific role is moisture vapour management, and it performs that role properly only when covered by a mid-layer that shields it from the outside environment.

Flatlock seams eliminate the traditional seam ridges that, under a rucksack or a harness, create pressure points after hours of wear. Raglan sleeves have no shoulder seam and follow arm movement without pulling on the torso — relevant when wearing a plate carrier over the top or keeping a rifle shouldered for extended periods. The thumb holes at the cuff anchor the fabric at the wrist and prevent the sleeve from riding up when pulling on a glove or lowering the arm: a practical detail that proves its worth when dressing quickly or in the dark.

Key points

• Weight of 156 g: adds warmth without noticeable bulk under a uniform or softshell.
• Technical polyester that moves moisture away from the skin, reducing sweat-induced cooling during breaks.
• Flatlock seams throughout: no friction points under harnesses, belts or rucksacks worn for long periods.
• Raglan sleeves for full freedom of shoulder movement, even with kit on.
• Thumb holes that lock the sleeve at the wrist during glove changes or kit set-up.
• Available in 7 sizes from XS to 3XL to cover a wide range of body types.