The Epic Series has many of the same sick features as our highend wetsuits, including 100% Ultraflex neoprene, double seal neck closure, LSD (lumbar seamless design) and re-engineered covert blackout zip. Clean graphics and sharp style lines make the Epic the best value in the industry.3/2mmLumbar Seamless Design (LSD)Updated Velcro closureGlued in covert zipper contruction with Back-out zipperSource: www.oneill.com