Motion Pro is dedicated to producing the most versatile, unique and durable products for professional and home use. Motion Pro tools are designed to be simple to use, yet durable enough to withstand the harshest conditions. One of their goals is to offer tools of convenience. Do it right the first time with Motion Pro Tools. Precise four channel vacuum indicator designed specifically for intake synchronization of engines with multiple carburetors or throttle bodies (maximum vacuum rating for this tool is 40 cm Hg). New mercury-free design uses non-toxic manometer fluid. For use with any 2, 3 or 4 cylinder four-stroke motorcycles. Spill-proof design means the tool can be stored in a horizontal or vertical position. Easy-to-read scale for precise synchronization. Unaffected by barometric pressure changes. Includes hang hook to clip onto the handlebars for easy use.