This C.H. Hanson set comprises an angle snap & chalk reel. Together they allow accurate marking of plywood, drywall, OSB & other sheet goods. The dual fence backstop of the angle snap allows it to be used on the edge or corner of a sheet. The locking angle mark is ideal for repetitive marking/layout. The tool speeds up layout with the stringline for angles on all types of projects. It can also be used as a protractor with a plumb bob for finding angles & roof pitches.