United Air: fire-smoke dampers
The company says it will be introducing its new UL-approved, 1.5 hr-rated fire dampers and leakage rated fire-smoke combination dampers at the AHR Expo. Styles include curtain, crimped, and airfoil blade. According to the manufacturer, these specialized dampers are designed for use directly behind supply-return grilles, designed to provide easy frontal access to the damper and any accessories.
— United Air Division of Leaders Industries