This duct collar is used for connecting air ducting, including metal spiral ducts, flexible ducts, PVC pipes, etc. It's suitable for bathroom fans, extractor fans, chimney, tumble dryers, In-line extract fans, HVAC systems, dust collection systems, hydroponics setups, etc. They are widely used in homes, offices, kitchens, factories, and apartments. Specification Color: Silver Tone Material: Galvanized Steel Size: 150 x 0.6 mm /6 x 0.02 Inch (H*T) Round Base Diameter: 380 mm/15 Inch Outer Diameter of Interface: 300 mm / 12 Inch Mounting Hole Diameter: 4mm / 0.16 Inch Distance Between Adjacent Mounting Holes: 170mm / 6.7 Inch Packing List: 1 Pcs x Duct Connector Advantage 1. Make of durable galvanized steel material, sturdy, waterproof, moisture resistant and wear-resistant, good toughness and pressure resistant, not easy to deform, can be used for a long time; 2. The crimped design allows you to connect it with ducting easily, and the textured surface can improve grip when connecting with a flexible vent duct, reducing the risk of air leaks or disconnections. 3. Pre-drilled holes on the connector base ensure easy and secure installation. Instruction Easy to install: Connect the duct connector to a wall, floor, ceiling opening, or any other surface by using screws to fix it. Then connect the connector with the ducting. NOTE: Please choose the right size according to your needs. The product does not include screws