Centralized around core First Lite pieces, this kit is built to handle the heat using merino wool's ability to wick sweat quickly, keep ideal body temperature through thermoregulation, and fight scent with its inherent antimicrobial properties (which can't be washed out). Throw in our Klamath Quarter Zip, Fuse Zip Off Boot Top, and Catalyst Jacket and you've got a system that'll keep you warm down to 45 degrees Fahrenheit. If you have any questions, give our killer Customer Service Team a ring at 208-806-0066 or shoot us an email at info@firstlite.com.