The Hot Chillys Men's Geo-Pro Midweight Solid Zip T-neck is a relaxed fit base layer top made with interlock construction using MTF polyester yarns for fit, comfort and performance. Interlock construction creates a virtual double knit, insulating fabric with extra bounce and durability. MTF fibers move moisture off the skin and away from the body. Soft spun yarns utilize new technology for a super soft, lived in feel. Perfect as a year round performance base layer for snowboarding, skiing, and hiking; applicable to all outdoor needs as well as a great choice for your casual lifestyle.