24x18 1 Door Satin Aluminum Frame Enclosed Letterboard. Enclosed Changeable Letterboards: If you want your message to get across then spell it out in an Enclosed Letterboard from Ghent. Your announcement or listing will stay secure behind shatter-resistant hinged doors that come equipped with disc tumbler locks. An attractive letter panel with its precision grooves for easy letter insertion provides a long-lasting background for your messages. Interior case depth is 1-5/16" for both aluminum and wood units. A set of 3/4" letters numbers and characters is included. FREE SHIPPING!