The Starrett 818 automatic center punch with adjustable stroke is 5" long with a 5/8" (16 mm) diameter for creating a starter dimple without the need for a hammer. Internal parts and the punch point are made from hardened tool steel for wear resistance, and the handle is made from 818 aluminum alloy for lighter weight than all-steel punches. The punch has an adjustable stroke, which can be set by turning the knurled cap. It also has a built-in mechanism to center the dimple. The point can be removed for replacement or sharpening.

Center punches make small dimple marks in a workpiece to help guide a drill bit. Manual center punches have a metal shank with a point and are typically tapped with a ball-peen hammer to mark the material. Automatic center punches have an internal spring mechanism that enables them to mark the material without using a hammer, leaving one hand free for steadying the work.

The L.S. Starrett Company manufactures precision measuring tools, metrology and testing equipment, and saw blade products. The company, founded in 1880, is headquartered in Athol, MA.