Incra T-RULE18 Precision Marking T-Rule
Precise, versatile, and easy-to-use are the words which best describe the Incra 18-inch T-Rule - to 1/64-inch. Think of it as a combination square for marking or measuring that's simultaneously set to every scale position with perfect, instant accuracy.  There are micro-fine marking holes and slots at every scale line to instantly locate your sharp pencil or scribe exactly on target with zero uncertainty.