Digital reading. Combined photo measuring alternative mechanical contact measuring. Photo measuring. Point the instrument against a reflecting tape or contrast part on the rotating object. Measuring distance 50-150 mm. Contact measuring. Measuring rev/min or surface speed. Press measuring ring/point against center of the rotation object for rpm reading. Alternative press measuring wheel against surface of the object for speed reading. Memory for last measured value and max and min value. Supplied with english manual. Batteries ar not included. Battery 4 pcs 1.5V LR06.