SABCOM BEAM COMPASS - Self-contained, retractable metal beam calibrated for inches and millimeters Accepts standard 2mm drafting lead (included) For circles up to 72" in radius Great time and money saver in the layout of custom mill work, on the job and much more Useful for custom windows, window grilles, tables, trays, stools, turned wood bowls, drafting, sheet metal, signs, holes for vents, cabinets, sewer pipe openings, wood crafts, rough openings, cloth, furniture, cases, boat building