The Starrett Prosite® Protractor takes the error-prone calculations out of the process of mitre cuts. Simply set your saw to the angle that you read. Upside down or backwards, the reading is always correct. This easy-to-use tool has two scales. The 'Mitre Cut' arrow and internal scale indicate the exact mitre saw setting for an accurate mitre joint every time. The 'Single Cut' arrow and the outer scale indicate the exact mitre saw setting for fitting a single work piece to an angle. It is ideal for carpenters, plumbers and all building trades that require the measuring and transfer of angles.