FLUORESCENT EDGES - The Alvin Fluorescent Triangle 40°/60° is designed for accuracy with its refracted light that illuminates the edges. MADE OF POLYSTYRENE - Made of molded polystyrene with 0.10" thick with double-beveled inking edges and double-beveled center cutout finger lifts. IDEAL DRAFTING TOOL - An ideal ruling and measuring tool for most drawing and drafting applications, it features machine-finished and hand-polished edges that not only meets but exceeds government specifications. CONVENIENT - The center cut-out finger lift, that is double-beveled as well, allows quick and easy lifting and placement. With a poly bag that includes a hanging hole, it provides portability, accessibility, and convenient storage when not in use. Comes in five different sizes. A PROFESSIONAL'S CHOICE - Alvin has been the professional's choice for drafting tools and drawing supplies for over half a century.