Spherical Electronic Digital Tube Micrometer auto power off Part No. DM-01B Designed to measure the wall thickness of various tubing. The Tube Micrometers have two combinations of measuring faces (carbide tipped): spherical-flat type, and spherical type. Cylindrical anvils (perpendicular) are also available. With Ratchet Stop for constant force. With SPC output Data hold, Data output, inch/mm conversion (inch/mm models) Alarm: Low voltage Wipe down the object you want to measure and the micrometers anvil. Turn the thimble on the micrometer clockwise. Continue until the contact faces of the anvil and spindle meet each other. Turn the micrometer on and press the zero button if the display reads any number besides zero. Turn the thimble counterclockwise. This will raise the spindle and make a gap between the anvil and spindle. Place the object on the anvil and lower the spindle until it touches the object. Push the hold button to receive a measurement on the display. Move the spindle back and push the object aside. Turn the micrometer off.