Basic-duty boxes offer double-end, single-side, double-bottom construction for storage with or without shelving. Use boxes to store letter-size or legal-size files. Liftoff lid ships attached and tears off for use so no missing lids. Average amount of evenly distributed weight that can be safely stacked on top of each box is 450 lb. Storage box contains a high percentage of recycled material. This product was made from wood sourced from a certified managed forest.