Handheld and non- measurement,portable and safety. Can measure the moving speed,motion state and defects of kinds of high speed rotating objects. Wide range of applications,such as all kinds of rotor,motor,fan,gear joggle,tremor equipment diagnose etc. With large LCD Backlight display screen,convenient to read data in the dark. Low battery indication,data storage,with fine and coarse adjust,single and continuous adjust,easy to measure. This DT2239B is a handheld digital stroboscope,high reliability and portability. use it to measure the moving speed,motion state and defects of kinds of high speed rotating objects. It's widely used,such as all kinds of rotor,motor,fan,gear joggle,tremor equipment diagnose etc. Model:DT2239B Display:19999 Measuring range:60~19999RPM RPM:R / min,FRM:F / min Coarse tuning/Fine tuning: Less than 1000RPM: Coarse tuning:+/-10RPM/FRM Fine tuning:+/-0.1RPM/FRM More than 1000RPM: Coarse tuning:+/-100RPM/FRM Fine tuning:+/-1RPM/FRM Accuracy:0.05% Resolution: Less than 1000RPM:0.1RPM/FRM More than 1000RPM:1RPM/FRM Time base:10MHz quartz crystal oscillator Supply power:4 x 1.5V AA battery (Not included) Product weight:202g colour:gray Material:plastic size:Product size:210 x 75 x 55mm Package Contents: 1 x Stroboscope 1 x Leather Box 1 x User Manual Note: Do not point the flashlight at eyes Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.