Innate Mentor Storage Sac - 2012 Roll-top access with durable side release buckle gives a waterproof closure Stitch less radio frequency welded seams will keep contents drier longer and are much more durable than conventional sewing and taping which is used on many comparable stuff-sacs Translucent recycled urethane front window for locating contents at a glance without dumping everything out Patent pending O2-Flow one way compression valve easily and quickly removes excess air; The valve is protected by an lightweight internal housing that will stay flexible in cold temperatures Lightweight 30 denier fabric with double sided water-proof treatment won't leak or become saturated in wet conditions; The exterior has a water repellent coating which you'll really appreciate when in damp humid environs The inner side features a durable urethane laminate which has increased water resistance and durability over comparable coated and taped stuff-sacs