Following are the Main Functions of Tachometer :
(1) Rotation Speed
(2) Selection of units
(3) HOLD Function
(4) Minimum & Maximum Values
(5) Choice between optical & contact revolution counter
(6) Adjustable automatic shut-off
(7) Adjustable backlight

MEASURING ELEMENTS
Optical Tachometry :optical detection (photo transistor tip length 40 cm Max.)
Contact Tachometry :ETC adaptor for optical tachometry Probe.
Measuring Ranges : From 60 to 10,000 RPM (Optical Tachometery)
From 10001 to 60,000 RPM (Optical Tachometry)
From 30 to 20,000 RPM (Contact Tachometry)
Accuracy : ± 0.3% rdg .± 1 RPM (From 60 to 10,000 RPM - Optical Tachometry)
± 0.3% rdg.± 30 RPM (From 10001 to 60,000 RPM - Optical Tachometry)
± 1%rdg. ± 1 RPM (From 30 to 20,000 RPM - ContactTachometry)
Resolution : 1 RPM (For Optical & Contact Tachometry)
Measuring Units : RPM (Optical Tachometry)
RPM,m/min,ft/min,in/min & m/s
Display : 2 Lines 5 Digit LCD display
Cable : retractable,length 450 mm ,upto 2.4 m when released
Power Supply : 1 Alkaline Battery 9 V 6LR61
Operating Temperature :0...50 degree C
Weight :190g