Johnson's 406EM-S Combination Square features a self-aligning draw bolt, etched stainless steel blade with 1/8 inch, 1/16 inch, 1/32 inch and millimeter graduations, heavy duty 45 degree and 90 degree precision machined square head and a hardened removable scriber. A combination square is a tool used for multiple purposes in woodworking, stone masonry and metal working. A combination square can reliably measure 90 degree and 45 degree angles. The 45 degree angle is used commonly in creating miter joints. It can be used to determine flatness on a board known as the face side. It can be a rudimentary level for approximating level surfaces. A combination square can be used as a depth gauge or to transfer dimensions and the scribe can be used for marking the work surface.