Keyhole Mounting Plates 1-3/4″ tall x 5/8″ wide Used to join two surfaces together. Excellent for mounting shelves, cabinets, pictures and / or signs. The tapered plate insures a tight fit. If you make recessed cutouts on the back of your item for the plates, there will be no visible support showing. Our keyhole plates allow your items to be hung basically flush to the wall.