Translucent one piece acrylic Plexiglas drawing disc. A full 3/8" in thickness provides an extremely rigid work surface with excellent backlight capability. Precision cut to 18 1/2" outside diameter, and the standard 16 1/2" lip for seating in any light box or table with the standard 16 1/2" cutout. This unit has one plastic acme peg bar seated at the bottom. Please note: no double bar is available. Two finger holes allow for easy rotation when coupled with one of our light boxes or drafting tables.