Instead of squinting at that blur of lines along the edge of your old steel rule Incra has re-invented the steel rule by putting micro-fine holes at every scale position Using a T-square this guide draws perfectly placed horizontal lines with dead-on accuracy, with guide slots that wrap around any edges Rule Set that lets you mark precisely where you want Micro-fine holes at every scale position Perfectly placed horizontal lines with dead-on accuracy Guide slots wrap around any edges Helps you draw perfectly placed horizontal lines