For indoor use only. Indoor Enclosed Changeable Letter Board manufactured of custom extrude parts engineered to provided a durable and handsome cabinet. Felt fixed rear panels are designed to accommodate changeable letters with tabs spaced on 1/4? centers. Standard features include: Lockable doors, acrylic safety glass windows, continuous hinges, concealed mounting brackets and a slotted background in Black felt. Includes a set of 165 count - 3/4" Helvetica letters.