Any rotating surface may be touched by the cone convex tip, funnel concave tip, or speed wheel for instant results. Tachometer displays revolutions per minute (RPM) from 10.000 to 99,999 (resolution 0.001, 0.01, 0.1, 1). In addition, it reports results in feet per minute 3.0000 to 30,000, yards per minute 1.000 to 10,000, and meters per minute 1.000 to 9999.9 (resolution for all three is 0.0001, 0.001, 0.01, 0.1 depending on the revolutions displayed). Unit is designed to measure centrifuges, pumps, rollers, shafts, gears, motors, and moving surfaces. For accuracy, see chart. HOLD button freezes reading. Precision quartz crystal insures stable and repeatable results. Short sampling time provides answers in two seconds. LCD digits are 1/2-inch-high and may be read from 10 feet. Low battery condition is indicated on the display. Impact resistant ABS plastic housing protects the unit. To assure accuracy an individually serial-numbered Traceable® Certificate is supplied to indicate traceability to standards provided by NIST (National Institute of Standards and Technology). Supplied with a 9-volt battery (for thousands of readings for over a year). Size is 4-3/4 x 1-3/4 x 1-1/4 inches and weight is 4 ounces. Replacement battery Cat. No. CON1112.