This is the backpack that converts to a 3 1/2' x 3' single-person sandless mat. Made from 100% polyester with a patented dual-layer weave that acts as a one-way filter, the bag allows sand and dirt to pass through to the ground but not the other way. Its 3/4' cu. volume stores beachgoing items without the need to carry a separate blanket. Scraping one’s feet on the mat removes sand easily. Its looped webbing provides 10 different fittings to suit contents, and it has a detachable pouch for valuables. 24" H x 17" W x 1" D when flat; up to 30 1/2" D when filled. (1 1/2 lbs.)