This electronic digital caliper is made of hardened stainless steel, which can measure internal, external and height dimensions. this micrometer is an essential tool for the rod builder. I use this every day in my shop and would not be without it. Technical Specifications: Measuring range: 0-150mm / 0-6 inch Power: one 1.5V LR44 button cell Package: 1 x Electronic Caliper (battery included)  1 x English Manual 1 x Case