... limited warrantyCalibration procedures:When installing a new battery or press “HOLD” button more than 6 seconds, T ... .Put the unit on the flat surface, short press “ABS” button, “-1-” icon is blinking 6 ... is on the LCDRotate the protractor end for endShort press “ABS” button, “-2-“ icon blinking 6 ... LCD), put the unit on the surface of 25 degreeShort press ON/OFF button, change to relative measurement. ...