Fowler 52-008-024 Stainless Steel Extended Range Dial Caliper, 24" Maximum Measuring, 0.001" Graduation Interval, Face Color Black Dial graduations of 0.001", with one revolution equivalent to 0.100" Hardened stainless steel construction for corrosion resistance and long life Extended range for measurements up to 24 inches Knurled lock screw holds the sliding jaw in position to help ensure a consistent measurement Covered rack to prevent dirt and debris from clogging the gear, and to help prevent measurement errors