Spherical Anvil Tube Micrometers have a round anvil for measuring the wall thickness of pipe, tubing, and other curved surfaces. All have a ratchet-stop thimble with a speeder knob to reduce the time it takes to open and close the micrometer. A constant-force mechanism stops the micrometer’s spindle from tightening once it contacts the surface of the measured object. This ensures repeatable measurements and prevents over-tightening. When the spindle stops tightening, the thimble stops turning, but the speeder knob will continue turning with a clicking sound. This micrometer is coming in different variation like digital and analog other than that it comes in variation of single side ball ended and double side ball ended with different ranges.