CoolMax is a brand of specially engineered polyester fibers designed for superior breathability and moisture control to help keep feet cool and dry. DryMax athletic socks consist of two separate layers – a highly water-repellent inner layer and an absorbent, quick-drying outer layer – that draw moisture away from the skin as quickly and efficiently as possible. Although these designs were originally developed by separate manufacturers, many brands use similar technology in their athletic socks.