Hardened, stainless steel bar for long life. Rounded nose scriber cuts clean, sharp lines with smoothness and less pressure. Lock to hold the slide in position. Fine adjustment thumb roll for precision measurements. Hardened, ground and lapped base with finger grooves provides ease of movement. Scriber can reference zero from the bottom of the base to get the full 6" (150mm) usable range. Inch-millimeter conversion. Zero at any position. Manual ON/OFF with auto-off. Single, 3-Volt CR2032 battery. Linear accuracy: +-0.001" (+-0.03mm) Resolution: .0005" (0.01mm)