Callipers feature stainless steel construction for professional use. Four measurements-inside, outside, depth, step. Extra large LCD screen is easier to read. Professional quality hardened stainless steel construction. Precision ground measuring surfaces. Four button control panel power on/off switch (on/off)-zero setting at any position(set)-data hold function (hold)-instant SAE or metric conversion (mm or inch). With data output interface. Fine adjustment thumb wheel comes with high impact plastic storage case Four button control panel-power on/off switch (on/off)-zero setting at any position (zero)-data hold function (hold)-instant SAE or metric conversion (mm/inch).