Standard sizes are 4′ high and any length up to 24′. Standard installations consist of two, three or four sliding chalkboards and a fixed chalkboard, cork bulletin board or projection screen, or a combination of all three, on the rear wall. Sliding chalkboard panels are DuraWhite, Durasteel or Porcelain. All trim and chalkboard edging is extruded aluminum in dull satin finish. For ease of operation, chalkboards are top-suspended and glide easily over the extruded aluminum track on molded nylon rollers.