Details Icebreaker Size Chart Designed for maximum comfort and performance, the Impulse Training Shorts are made from Pertex® Quantum Air nylon fabric, which has an open weave for breathability as well as wind-resistance. Offering extended comfort and adaptability, these are the go-to shorts for when you want to take it to the next level, whether it's uphill, dirt track or cliff-face. Corespun fibers feature a nylon core wrapped in merino wool and natural TENCEL® for added strength and durability, as well as next-to-skin softness. Cool-Lite™ fabric in the long inner short and waistband wicks away moisture, and the waistband is adjustable, upping the comfort stakes so you can keep going for longer. Zippered hand pockets keep small essentials safe.