The MINI-MAX, Ultrasonic Bolt Tension Monitor, defines the state of the art in the measurement of the actual elongation produced by tightening a threaded fastener.  The MINI-MAX can measure the elongation very accurately in fasteners of virtually any material from 1/2 inch to 4 feet in length.  The measurement is achieved by determining  the change in the transit time, of an ultrasonic shock wave along the length of the fastener as the fastener is tightened by any method.  The on-board microcomputer automatically interprets this time measurement to display the time(nanoseconds), elongation, load, stress, or %strain from stretching a fastener.