4" Stick On Collar

A 4-inch stick-on collar is a round duct connector designed to be attached to flat surfaces (such as rectangular duct plenums, ductboard, or sheet metal trunks) without requiring screws or rivets for initial placement. Instead, it uses a self-adhesive flange or gasket to "stick" securely to the mounting surface. Once attached, it serves as a transition point between the main duct or plenum and a 4-inch round branch duct, allowing the connection of flexible or rigid round ducts for air distribution. Stick-on collars are used in HVAC systems for both supply and return air applications and are valued for easy installation, improved sealing, and labor savings.