An 8‑inch stick‑on collar (also called adhesive or press‑on collar / takeoff collar) is a duct accessory used to connect a round 8‑inch duct (rigid or flexible) to a flat surface (plenum, ductboard, sheet metal) with minimal mechanical fastening. Unlike snap collars or starting collars that require screws, rivets, or snap tabs, a stick‑on collar uses a built‑in adhesive gasket or pressure‑sensitive adhesive (PSA) on its flange to “stick” to the mounting surface, forming an initial seal.

It is designed for HVAC applications (supply or return branches) where ease of installation, reduced air leakage, and labor/time savings are prioritized. Some models include extras like scoops, dampers, or pre‑crimped edges to facilitate duct connection.