Fowler 30 – 50mm Deluxe Internal Digital Caliper Gage Features: • Perfect for measuring bores, thickness, o-ring and snap-ring grooves. • Fast and accurate measuring results • Absolute and relative measurements • Operates on a 3V lithium battery • Inch/metric conversion • Large LCD display • Peak measuring modes • Suitable for workshop use • Data transfer via RS 232 • Includes test certificate, operating instructions, battery, and hexagon socket screw key