Fowler 52-025-012 Stainless Steel Heavy Duty Dial Caliper, 12" Maximum Measuring, 0.001" Accuracy, 3.5" Jaw Depth Dial graduations of 0.001" or 0.05mm, with one revolution equivalent to 0.100" or 0.5mm Hardened stainless steel construction for corrosion resistance and long life Thick frame and long jaws for use in rigorous environments Knurled lock screw holds the sliding jaw in position to help ensure a consistent measurement Knife edge top jaws to measure threads, slots, and recesses