HAJKER PRO 30L Winter Rolltop Daypack is a waterproof ultra-durable daypack with a rolltop opening, made for highspeed activities and gnarly expeditions. It's equipped with our bounce free No Dancing Monkey™ 2.1 harness system and waist support belt that makes the pack stay put on your back without cramping your style. The HAJKER PRO 30L WINTER also has our revolutionary Thermo Cell insulation technology that uses the body heat, a thin permeable membrane and space suit technology to prevent the drink tube and bite valve from freezing.