Engineered to mount on walls between studs that are 16" on center using pre-drilled holes and mounting hardware. Electronic lock activates the two live-action locking bolts. Includes a key rack and key tags. Concealed hinges add security. Inside there are two removable shelves and a document folder for receipts, passports or other papers. Straps allow pistols to be mounted to the back. Tested and listed as a California D.O.J. firearm safety device. Dimensions: 20-5/8"H x 13-13/16"W x 3-3/4"D.