The C.H. Hanson Angle Snap and Chalk Reel Set for accurate marking of plywood, drywall, OSB and 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 and roof pitches.