REFLECTIVE TAPE:Reflective tape must be attached to measure RPM.Note: If measuring laser objects be sure to stick reflective paper. TECHNOLOGY & DISPLAY: The use of microcomputer technology, anti-jamming technology and other advanced technology, can accurately measure the speed value. Large screen liquid crystal display, clear reading. ACCURATE MEASUREMENT:Wide measuring range(2.5RPM to 99999 RPM);High resolution(0.1RPM or 1RPM).Accurately measure the speed of motors and machine parts.Measuring distance: (50- 500mm). WIDELY USE:Used in of motor, metal and wood cutting lathes, electric fan, paper making, fiber manufacturing, washing machines and automotive manufacturing etc.It is not support for sawmill or lawn mower. PORTABLE:Compact and .Easy to take out . Dimension: . 131 (L) x 70 (W) x 29 (D) mm/ 5.16 x 2.76 x 1.14inches., Weight: 0.29982867632 Pounds, Manufacturer: Ehwisbe