Abstract: A box for use as a file container or the like characterized by a single piece, corrugated cardboard blank that is foldable into a completed configuration with lockable top panels that are openable and closable to allow access to the interior. The end portions of the sides have locking tabs so as to be locked into position and facilitate folding the rest of the box into place. The ends have two outer portions that fold over the end portions of the sides to make a triple strength end with vertical corrugations for stack strength. Hand holes are provided to facilitate lifting the box. The locking tab on one of the top panels is provided at each end of a foldable flap that folds over the other top panel. The locking tabs lock into locking aperture at each end by simply folding down.