Outer Diameter of Interface: 147 mm / 5.79 inch; Overall Size: 197 x 1 mm / 7.76 x 0.04 inch (L*T); Color: SilverAdvantage: 1. Made of durable Galvanized Iron, which has high hardness and high temperature resistance, not easy to deform and corrosion, moisture-proof and fade resistant, can be used for a long time; 2. The side is designed with a rotary handle, which can adjust the air volume from multiple angles and is easy to operate; 3. The interface is smooth and flat, easy to disassemble and install. Silicone rubber ring design can prevent the air duct valve from leaking when it is closed.Instruction: Easy to install, just simply slide the volume damper into the pipe you are attaching to, and fix with pipe clamp and tape.