Steel Rule is a measuring instrument used as a standard for measuring materials. It is made of stainless steel. The most convenient for the general purpose is a 12 inch rule as shown in below schematic –
For small jobs, a pocket rule 6 inch long is very useful. In measuring, the graduation should be as close to the work as possible. The steel rule being the most common measuring instrument, most not be used carelessly . The rule must be properly oiled to prevent from corrosion.