A step beyond commonplace mercury ‘carb sticks’, this device sports digital accuracy and no moving springs or diaphragms. Powered by an included 9 volt battery, the TwinMax is suitable for both carbureted and fuel-injected engines of 2, 3, or 4 cylinders. A very easy to use and useful shop tool that you’ll have fun with the first time you use it. 4.25"×3"×1.5". For bikes without vacuum synch ports one 5mm threaded adapter per cylinder is required.