SPECIFICATIONS: PHOTO TACHOMETER MODEL: RPM33 MAKE: EXTECH LARGE 5-DIGIT BACKLIT LCD SCREEN BASED ON MICROPROCESSOR WITH QUARTZ CRYSTAL OSCILLATOR TO MAINTAIN HIGH ACCURACY STORE/RECOVER 10 SETS OF DATA IN MEMORY WITH 4 PARAMETERS (MEASUREMENT, MAXIMUM VALUE, MINIMUM AND AVERAGE) VARIOUS RPM MEASUREMENTS (PHOTOTACOMETER AND CONTACT TACHOMETER) AND LINEAR MEASUREMENTS OF SURFACE VELOCITY/LENGTH (CONTACT TACHOMETER) USE A LASER FOR NON-CONTACT MEASUREMENTS OF GREATER DISTANCE, UP TO 1.6 FT (500 MM) INCLUDES CONTACT WHEEL FOR RPM OR SURFACE VELOCITY/LINEAR LENGTH, 9 V BATTERY, REFLECTIVE TAPE AND SOFT CASE WITH CALIBRATION CERTIFICATE FOR CONTACT VELOCITY AND PHOTO CONTACT.