There are many of us who know only one type of season. The year-round one. We can't stay locked indoors just because it's -10°C outside and the countryside is covered in snow and ice. Our favorite „bagel“ hammock together with the tarp for bushcraft look sadly at us from the corner of the room, and running shoes or streetworkout gloves are making it more and more clear that they need to get some fresh air. Eventually we give in to that tempting call and let the inner fire in us do what it does best. Push our limits and teach us something new. However, winter is a relentless companion, and sooner or later you will start considering an essential item for low temperatures – thermal underwear.
To give you the best idea, we'll show you right away two models. Both will be from one of my favorite brands, the Polish Helikon-Tex. Specifically the thermal underwear US Level 1 and US Level 2.
Members of security forces in Europe, as well as in North America, or bushmen know Helikon very well. It has been engraved in the hearts of adrenaline enthusiasts for a long time already, specifically since 1983. Its products are the result of close cooperation with professionals from Polish armed forces as well as the civilian sector. The patrons of their product lines are well-known names, such as Instructor Zero for the Range line or one of my favorite woodsmen - Dave Canterbury for the Bushcraft line.
US Level 1 Thermal Underwear
US level 1 is designed for active movement in a cooler environment. In terms of color, we can choose between black and olive green. The manufacturer practically packs the top and bottoms together. There's not much accounting for disproportions. However, the underwear has sufficient elasticity and reserve in the cut, so longer arms or a smaller beer belly are not a problem at all.
I was surprised by the length of the top. It is extended all the way to the pelvis. Even with a sudden movement, my lower back was not exposed.
The sleeves have thumb holes with a stronger hem on both ends. There's no need to worry about them tearing even with a sudden lunge. When the thumb is inserted, the sleeve covers most of the wrist.
Perfect moisture and excess heat management
It can also be worn very comfortably in the classic way, discreetly under a shirt. Both the top and bottom part have reinforced additional stitching in critical areas. Both pieces are made of 100% polyester, but with a cleverly designed fabric structure. The fabric is in fact woven in the form of a mesh, where small breathable sections can be seen in the material. Thanks to this, the fabric is more elastic, and more importantly, it perfectly wicks away excess heat and, above all, moisture.
I appreciated it most during outdoor training. Running or street workout was no problem at all, and I enjoyed it more than with my traditional cotton underwear. Outside it was -2 °C, yet I felt pleasantly warm and this without the unpleasant feeling of overheating. At the same time, it did not restrict me even during the most intense movement. The top base layer also worked well for indoor training. Of course, it doesn't replace Quick dry, but training in it was more comfortable than in a regular T-shirt.
As for me, I give Level 1 two thumbs up. It delivered what it promised, at a good price, and showed greater potential than I originally expected from it.
That's one down. Let's take a closer look at its warmer sibling.
Level 2 base layer
US Level 2 is, at first glance, constructed differently. The main reason is that it is designed for a different purpose. Primarily for passive activities in colder weather, such as a winter/autumn bivouac in the open air, fishing, or hunting from a stand. Compared to Level 1, it uses a differently designed fabric. It is a blend of 95% polyester and 5% spandex. Spandex gives the fabric the necessary elasticity.
At first glance, the massive extended zipper on the chest catches the eye, ending approximately at the lower part of the sternum. Level 1 stood out for its simple cut. In the case of Level 2, however, we find a whole host of distinctive features, some of which are shared. Just like the first one, the base layer top has an extra long cut and sewn-in thumb holes on the sleeves. The bottoms feature a taller opening in the front pelvic area. Both pieces fit well and at the same time do not restrict free movement in any way.
Differences between Level 1 and Level 2
The blended material and long zipper on the chest, we have already outlined. The fabric is not smooth, but grid-textured. It is made up of small squares, thanks to which it warms pleasantly, while also allowing excess heat and moisture to escape. The top has a high collar that covers the neck well, but without the unpleasant choking feeling known from tight turtlenecks.
As a bearded man, I quite appreciated the fabric triangle near the chin, at the end of the zipper. It works as a kind of flap, with which I can cover the metal end of the zipper after zipping up. At the same time, it gets rid of the unpleasant feeling a cold metal zipper pressing into the chin can create.
I was surprised during sewing by the extra reinforced seams, which are present on both the top and the bottoms at the most stressed spots. It is immediately clear that besides comfort, the manufacturers also thought about sudden movements and strain.
The wide elastic waistband on the bottoms held excellently, I didn't have to adjust it even once for the whole day and night. It didn't ride up on my lower back, nor did the bottoms slide down into my pants. At the same time, neither the top nor the bottom elastic cut into the waist or ankles.
I am not one to feel cold easily. Even in winter, I tend to wear transitional jackets with a fleece hoodie as the base layer. That's why the level 2 felt insanely hot on me. Wake-up call, breakfast, walk to the train to work. Early morning at -10°C wearing just regular sneakers, winter Bobr socks (by the way, a really great combination with Lvl 1 and Lvl 2), and classic Rip-stop BDU pants from Pentagon. Not counting the socks, it's more of a combination for a nice spring day than for cold sub-zero temperatures, at which even penguins consider changing their address☺. Under the pants, however, I wore Lvl 2 bottoms. Thanks to that, my legs were experiencing a summer vacation in the Mediterranean. 
To sum it up, Helikon-Tex clearly has a team of creative and practically minded designers. Both thermal underwear sets met all my requirements without compromise.
They are a good example that quality items don't have to cost a lot and can be simple and practical at the same time.
Finally, I want to wish you as much fun and pleasant experiences with the thermal underwear as I had. Whether it's with one, the other, or both versions. They will help you gain new experiences and go beyond your original horizon even in an unfriendly cold environment, which most people avoid for their own comfort. Winter has its own unique charm, which remains hidden for most people, simply because of their comfort zone.
