Features: Efficiently connect square ducts to round ventilation systems with duct connectors flanges, crafted from plastic for corrosions resistance and long time performances in heating, cooling, or exhaust applications. Featuring pre drilling screw holes for easy wall mounting and integrated hose clamps, this adapters ensures airtights airflows between appliances and ducting systems. Designs for homeowner, contractors, and enthusiasts seek ventilation solution for dryers, kitchen supplies, or hydroponic setups requiring square to round conversions. Optimizes airflows in laundry room, commercial kitchens, or indoor gardening space by secure attaching exhaust hoses to inlines fan, ranges, or HVAC systems this universals flanges. The pmolded square to round designs minimizes air turbulences and leakage, ensuring energy efficient operations of ventilation equipment while maintaining indoor air standard. Specifications: Materials: Plastic Size: Diameter 9.92cm/3.91invh Package Includes: 2pcs Flanges Interfaces note: 1.Please allow 1-2cm errors due to manual measurement, making sure that you will not mind before order. 2.Due to the differences between different monitors, the picture may not reflect the actual color.