Environmentally friendly boxes with secure locking lid offer a medium-duty construction for moderate stacking and archiving inactive letter-size or legal-size files on shelves. FastFold setup feature makes box assembly fast and easy. Deep, locking, liftoff lid stays in place for secure file storage. Boxes are made of 100 percent recycled material with a minimum of 100 percent post-consumer content. Average amount of evenly distributed weight that can be safely stacked on top of each box is 550 lb.