This Starrett Dial Caliper 120A-6 has sharp black graduations every 0.100" on the no-glare, satin-finished stainless steel bar, and graduations on the dial every 0.001". One full resolution of the dial is equivalent to 0.100". It features knife-edge contacts for measuring both inside dimensions (ID) and outside dimensions (OD), and can be used to scribe parallel lines on the workpiece. This caliper can be used with one hand only through the fine adjustment roll with the thumb. The lock screw locks the dial bezel and holds the sliding jaw in position. The depth rod is integrated into the rack of the caliper, unlike many calipers which offer a detachable depth rod, or none at all. The hardened stainless steel components, including the bar, measuring surfaces, rack, gears, and depth rod, are all corrosion resistant. Positive split gear anti-backlash control offers increased accuracy over standard gear configurations. The rack teeth point down to keep foreign matter from clogging the gear operations. This prevents measurement errors where metal chips could interfere with proper caliper operation. The company, founded in 1880, is headquartered in Athol, MA.