Features: Accuracy engineered plastic air capacity control valves with 90 degree adjustable handle ensures accurate airflows regulation and long lasting durability in HVAC systems. Features ABS construction for superior air tightness and tool free installation compatible for 75 to 200mm duct diameters. Essential for HVAC technicians, industrial maintenance crews, and DIY enthusiasts upgrading ventilation efficiency in commercial or residential spaces. Optimizes airflows control in laboratories, hospitals, or coastal buildings requiring corrosion resistant valves for humidity inclined environments. Manual butterfly valves design doubles as a reliable check valves, maintaining directional airflows integrity across 20°C to +80°C operating temperatures. Specifications: Material: pp Size: No. 1: Inner diameter: 7.5cm Wall thickness: 0.3cm No. 4: Inner diameter: 11cm Wall thickness: 0.3cm Type: 2 for option Package Includes: 1xAirflow Control valves note: 1.Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. 2.Due to the difference between different monitors, the picture may not reflect the actual color of the item.