For outdoor use. Enclosed Changeable Letter Boards are manufactured with custom extrude parts engineered to provided a durable and handsome cabinet. Fixed rear panels are vinyl and 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 vinyl. Outdoor models feature a vented case for moisture reduction, weatherized rear panel and a thick rubber door seal. Includes a set of 165 count - 3/4" Helvetica letters.