The General Tools and Instruments 843/1 Pencil Compass and Scriber is for marking contours and circles. Positive wing nut adjustment. Full-length hardened steel pin in metal frame for greater rigidity. Constructed of brass plated steel.GENERAL TOOLS - THE PRECISE TOOL FOR DOING THE JOB EXACTLY RIGHT. Offering over 1,000 tools, we?re proud to provide tradesmen, craftsmen and DIYers around the world with a broad range of affordable, specific-purpose mechanical hand tools and precision measuring and inspection tools.For inquiries, please contact our Customer Service Department at 212-431-6100. We strive to provide our customers with 100% satisfaction.WORK SMARTER, MEASURE BETTER & BE MORE PRODUCTIVE WITH GENERAL TOOLSFrom the ManufacturerUse this pencil compass and scriber to scribe and draw circles. It has a positive wingnut adjustment. The full length hardened steel pin is in a metal frame for greater rigidity. It is constructed of brass plated steel.