The JL Drywick Ziptech just what you need for those cool mornings and hard work outs. Did you know Heirloom is a nylon fiber workhorse. A full-stretch, mid-weight strong yet supple fabric. Heirloom is a super soft, super durable nylon fiber. Not like the shiny nylon of the 70’s. Technical Properties: Wicking, Anti-microbial, Microfiber Technology, and high UPF rating.