THIS AIR FLOW METER IS USED TO ACCURATELY BALANCE THE AIR FLOW ON CARBURETORS, THIS UNIT DOES NOT DISRUPT THE AIR FLOW WHICH CHANGES THE MIXTURE LIKE SOME OF THE CHEAPER UNITS IN TODAY'S MARKET. SYNCHROMETERS, ARE GREAT INSTRUMENTS FOR THE CONSCIENTIOUS TUNE UP SPECIALISTS. IT PROVIDES PRECISE INFORMATION ON ALL MULTIPLE CARBURETOR SYSTEMS AT IDLE AND MID RANGE TRANSITION MODES AS WELL AS QUICKLY SPOTS JAMMED SHAFTS AND MISALIGNED THROTTLE PLATES.