The General Tools Vernier Caliper can make inside, outside, depth and step measurements in inches or millimeters. Caliper lock for repetitive measurements. Slide lock for gaging. Friction roller simplifies adjustments. Measurement range: 0 to 5 in./125mm. Graduations: Every mm and 16th of an inch (main scale); every 0.1mm and 128th of an inch (vernier scale).