Imagine a piece of clothing that keeps you warm when it’s cold, cool when it’s hot and is unbelievably lightweight. It would be the answer to all of your everyday needs—and we have it right here. Gear up and get in the game with our latest innovation: Core Temp.

Our Core Temp styles are engineered with 37.5® Technology to help stabilize your body temperature. What does this mean for your style game? Better performance, higher stamina and optimal energy. The technology helps you maintain your core body temperature (37.5º Celsius) so you don’t waste energy heating up or cooling down. It’s scientifically proven to increase stamina by conserving energy. The coolest part? You won’t believe where it comes from.

These performance styles were originally your favorite gym styles, until now. We’re excited to welcome this performance fabric into your 9-5-9 wardrobe, and we think you will be too. To help explain the hype, we asked Jane Ibarra, the brains behind our innovative fabric development department, to break down the benefits of our new Core Temp line.

It’s got a performance element, but still feels true to the man, the brand and the customer.”

37.5® Technology is a patented innovation that comes from volcanic sand—particles that trap moisture and keeps the wearer at their optimal core temperature. The particles are spun with other fabrics and woven together to create a special blend. The coolest part: the technology is inspired by the natural benefits of sand baths on Japanese volcanos, and it’s single-sourced from a top-secret location. “We’re using the earth-given, temperature-regulating abilities of the active volcanic sand, and mixing in natural fibers like cotton from there,” Jane says.­­­ This means you get the comfortable feel and familiar look of cotton with sustainable performance technology.

What excites Jane most about Core Temp isn’t its many features, but rather that the features stem from the fiber of its being. Oftentimes, performance qualities are added through a finish, which leads to several negative side effects: the finish can wash off over time which means that the product will lose its benefit—or worse, the washed-off finish can harm the environment. “One of the coolest things about Core Temp is that we’ve been able to embed that temperature-regulating technology directly in the fiber, which means it won’t wear off over time,” Jane tells us. “Even better, it’s not harmful to the environment.”

The idea is to stay true to who we are—having a natural fiber as our base…but blending it with something that gives it the elevation with performance.”

Jane describes Core Temp as your favorite styles but with invisible technology: It has the stretch that you’ve come to love, but it also has quick-drying and wrinkle-resistant properties, as well as heat-regulating technology. Jane reveals that the material was originally made for mountain climbing and severe weather temperatures, but we’ve been able to give it the same look and feel as something you’d wear to work or on a night out.

The idea of it coming from a volcano is kind of amazing.”

Ready to feel the power of natural performance? Check out our feature on Core Temp, where pro athlete Jared Goff puts these forces of nature to the ultimate test. Then, hear it from Jared himself in our exclusive Q&A with the pro.

This article was originally published in May 2018 and has been updated for accuracy.