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37.5® Technology Simplified

37.5 Technology helps hunters cool down quicker when hot, warm up faster when cold, and captures scent to mitigate odor.

37.5 in the Field

Variable conditions are part of the hunt, and the ability to adapt to them defines a skilled hunter. When you're out in the field, the forces at play are bound to change; temps drop, the sun beats down, rain moves in, the wind blows, and snow falls. Whether you're chasing whitetails from the stand or elk over ridgelines, your adaptability needs to be matched by your hunting clothes. Products made with 37.5 Technology work with your body to help cool you when you're hot and keep you warm when you're cold, keeping you in the sweet spot where your body performs best regardless of the weather or your activity level. By integrating 37.5 Technology into our baselayers and outerwear, First Lite makes layering systems that allow hunters to go farther and stay longer. To see how 37.5 helps deliver on our founding principles, keep reading.

Benefits to the Hunter


Provides dynamic thermoregulation of body heat, helping keep your core temperature at an ideal 37.5°C.

Scent Control

Traps odors (human signature) and releases them when laundered, helping fabrics keep fresher for longer and assisting with "scent" mitigation.

Increased Dry Rate

Reduces a fabric's drying time, while simultaneously requiring less body energy to do so.

Improved Stamina

Scientifically proven to reduce the amount of energy your body uses to manage core temperature, increasing stamina and boosting athletic performance by up to 26%.

Sweat Prevention

Removes moisture in the vapor stage, delaying the onset of liquid sweat. This helps keep your skin's microclimate at the optimal relative humidity of 37.5% and reduces the amount of moisture present for bacteria (odor) to form.

Permanent & Natural

37.5 Active Particles are made from naturally occurring volcanic minerals, permanently embedded at the fiber level. Unlike chemical finishes, it will never wash out and works for the entire life of the product.

Technology Up-Close

A 37.5 active particle at a microscopic level. The particle's composition draws moisture vapor and excess heat away from the body.

37.5 active particles permanently embedded into a single fiber. The particles will push captured excess heat and moisture towards the exterior of the fabric.

How the Technology Works

Layering Increases the Benefits of 37.5 Technology

37.5 Technology helps your body thermoregulate through active particles permanently embedded into fabrics that attract moisture vapor and move it away from the skin. The more of these active particles present in a fabric or clothing system (from baselayer to outerwear), the faster they are able to move this humidity away from your skin. Simply put, the more products you wear that are made with 37.5 Technology, the better it works.

37.5 Baselayers

37.5 Western Outerwear

37.5 Whitetail Outerwear