Precise four-channel vacuum indicator designed specifically for intake synchronization of engines with multiple carburetors or throttle bodies. Includes manometer fluid, hoses, 5 mm adapters, in-line restrictors and instructions. Spill-proof design means the tool can be stored in a horizontal or vertical position. For use with any two-, three- or four-cylinder 4-stroke engines. 5 mm adapters are used on many Honda and Suzuki models. Includes hang hook to clip onto the handlebars for easy use. Most Kawasaki models do not need adapters. Unaffected by barometric pressure changes. Mercury-free design.