Application: To 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 trucks Adapter Sizes: 35mm, 39mm, 44mm, 48mm ( can expand 4mm) Package Include: 3x rubber bushing adapters 1x 2" Gauge 1x Clear Hose 1x Carry Case Note: * Please feel free to contact us for whatever we can help. (Instruction Included. (If not, we could offer you the E-book version. )) * The silver adapter is available for extra use with European connectors that are needed * Box Color: The color of the box is random Box Color: The color of the box is random Box Color: The color of the box is random