Recommended series: Rho Warmth, Satoro Merino Wool
 
As a leading brand in the outdoor field, Arc'teryx has the ultimate pursuit of new craftsmanship and new technology. In terms of thermal underwear, Arc'teryx has added technologies such as silver ion treatment, core spun technology, and single-layer hot pressing. Its product line is strictly divided according to function, and the bottom layer has three series: Phase, Satoro, and Rho. Phase is a quick-drying series with almost no warmth function, so only the merino wool series Satoro and the thermal series Rho can be regarded as thermal underwear in the true sense.
 
The insulated Rho is the base coat with the highest thermal insulation rate for Arc'teryx. The exterior is light and shiny, the inside is fleece to the touch to help keep warm, and the Polygiene silver ion treatment is antibacterial and deodorant.
 
Rho can also be subdivided into Rho LT and Rho AR, LT (LIGHT) is an entry-level existence in most series, featuring lightweight materials for three seasons. Rho LT uses a lighter Torrent 190 fabric, which is woven from polyester and spandex, which has strong moisture absorption, elasticity and more freedom of movement, and the domestic price is about 1,600 yuan, which is almost twice that of foreign countries. AR (All Round Use) can be regarded as an advanced model of LT, it has increased the thickness, changed from lightweight to medium and heavy, has stronger warmth, is suitable for slow activities in cold temperatures, and the price at home and abroad is comparable, about 2000 yuan for a top.
 
The Merino wool collection Satoro AR is composed of 81% merino wool, 12% nylon, 7% spandex. It has the temperature control function of merino wool products, comfortable and skin-friendly, moisture-absorbing and perspiration-wicking, sunscreen and odor suppression. In addition, Nucliex STR 180 core spun technology is used to add tough nylon yarn to the Merino wool fiber, which enhances the durability of the series and solves the problem of low durability of Merino wool clothing. Although it claims to use wool with a higher quality count, compared with Smartwool Merino 150, there is not much difference in body feeling, and the price of about 1400 yuan is much more expensive.
 
The details reflect Archaeopteryx's quest for functionality. Since the wool cuffs are easy to wear loose, the Satoro collection has a shrink cut of the cuffs. At the same time, both series of thermal underwear are interlocked, and a pocket design is added, which uses a single-layer hot pressing technology for sewing, which can reduce stitching and keep the fabric intact. Considering the different physiology of men and women, the position of the pockets is also slightly different, with the women's model located on the arm and the men's model located on the chest.
 
Although Arc'teryx has good performance, it is several times more expensive than other brands, and it is difficult to talk about high cost performance, so it is more suitable for people with a loose budget.