The Starrett C183 Steel Protractor is a highly useful and accurate tool for setting bevels, transferring angles, small squaring tasks, checking cutter clearances within certain limits, and many other applications. Includes double graduations from 0-180_ in opposite directions permitting the direct reading of angles and supplementary angles. The back of the tool is flat for ease of use. The blade can be locked firmly at any angle by the lock nut. The protractor also includes a satin chrome finish for ease of reading and resistance to rust. 6" (0-180°) with Rectangular Head rust.