Digital Photo, Contact, Surface Tachometer

This Photo Tachometer also features contact measuring and surface speed measurement. Giving three operations in the one unit.
Housed in a light weight ABS housing this tachometer has the exclusive one chip
MICROCOMPUTER LS1-circuit and crystal time base to accurately offer high accuracy through each five digit 10mm liquid crystal display.
The accuracy of a photo tachometer is the correct method of timing and tuning of diesel engines where variance of + / - 1rpm from manufactures governor specifications will reduce power and increase fuel consumption.
Rotative Velocity: 2.5 to 99.999r/min (Photo) 0.5 to 19.999r/min (Touch).
Surfaced Speed: 0.05 to 1999.9m/min 0.2 to 6560ft/min.
Laser Detection Distance: 50 to 600mm .
Resolution: 0.01 / 0.1 / 1 .
Memory: Max / Min / Last Value .
Accuracy: (0.05%N+1d) .
Power Supply: 4 x 1.5V AA(UM-3)battery .
Dimension: 215 x 74 x 32mm.