ApplicationTo reduce cooling system refilling time and prevent the air flow into the system Connect with air pump and create a vacuum to remove trapped air in cooling system for most cars and light trucksSpecificationAdapter Sizes:35mm, 39mm, 44mm, 48mm( can expand 4mm) Package Include: 3x rubber bushing adapters 1x 2\" Gauge 1x Clear Hose 1x Carry compatible for Case Box Color: The color of the box is randomNotePlease feel free to contact us for whatever we can help.(No Instruction Included)