This is the 4th Element J2 Men's Drysuit Baselayer - Top ONLY Features: Developed for J2 caving expedition Tested for 19 days, 24 hours a day Anti-microbial silver ion technology Lightweight and compact Fast wicking extreme performance Perfect for extended drysuit diving Men's Top: 91% Polyester / 9% Elastane Baselayer protection for extended range diving. Developed using antimicrobial silver ion treatments, this fabric was tested in the extreme environments of the J2 cave system, one of the deepest in the world. It is stretchy, warm, and won?t let you down. A simple, close fitting design with flat seams for next to skin comfort offers the perfect solution under any drysuit underwear. This top is not only easy to don, it has good aesthetics and is extremely comfortable thanks to excellent all-way stretch fabric and flat seams.