The 10" Start Collar is a galvanized steel round duct connector designed for secure HVAC ductwork connections. This versatile fitting links round duct to sheet metal, duct board, plenums, and ventilation systems in residential and light commercial applications. Its durable galvanized construction resists corrosion while providing reliable performance in supply air, return air, and general ventilation systems. Built for professional HVAC installation where a dependable round collar connection is essential.