Sugatsune says its new door straighteners can protect a door from future warping. Recommended for assembly under the cover of wood veneers. the straighteners are to install recessed or concealed and can be used in hollow wood panel applications. FeaturesFully concealed door straightenerRecess mount under door laminateMinimum thickness 1/2 (12mm)10mm (3/8) adjustment can be made;; adjustable at the top of door with M4 allen key (not included)For door height 2030~2450mm (80~96). Bar must be cut to lengthup to 16-1/2 (420mm)Fasteners not includedSpecificationsSize: 19 in.