In addition to accurate measurements and precise construction, this tool is magnetic securing to metal surfaces. Perfect for drawing angles and shapes for demonstration. Constructed of quality plastic, these instruments are durable and affordable.WARNING CHOKING HAZARD: Small Parts. Not for Children Under 3 yrs.WARNING: This product contains small magnets. Swallowed magnets can stick together across intestines causing serious infections and death. Seek immediate medical attention if magnet(s) are swallowed or inhaled. Not for children under 3 yrs.