How it connects
The end of a helical flexible or semi-rigid duct is manually screwed into the collar; internal helical ridges engage duct corrugations to create a mechanical hold and air seal without tools, tape, or clamps.
Male and female halves
Female internal threaded collar that mates with the male exterior helix/corrugation of 4-inch flexible dryer transition ducting.
Usually connects to
- 4 in. flexible aluminum foil dryer transition duct
- 4 in. semi-rigid aluminum flexible dryer duct
Common sizes
- 4 in. (102 mm) nominal duct diameter
Where it is used
residential laundry dryer exhaust ventingdryer transition ducting
Variations
- Round-to-oval threaded dryer adapter
- Round-to-round quick-connect threaded dryer coupling
How to recognise it
Recognizable as a molded plastic (often polystyrene or polypropylene) cylinder or sleeve with coarse internal helical ribs or thread segments matching the spiral pitch of flexible ducting.
Often confused with
| Confused with | How to tell them apart |
|---|---|
| Smooth round sheet metal duct slip collar | Smooth slip collars require hose clamps or foil tape to secure flexible ducts, whereas helix-engaging collars feature internal helical molded ribs that screw directly onto the duct spiral. |
| Standard pipe threads (NPT/G) | Pipe threads have fine machine V-threads meant for rigid threaded pipe, unlike the wide (~6 mm pitch) rounded coarse spiral rib designed for flexible wire-reinforced ducting. |
Also called
Threaded dryer duct connectorScrew-on dryer duct collarSelf-threading flexible duct adapterTwist-on dryer duct adapter
Good to know
Commonly seen on proprietary adapters and quick-connect kits (e.g., Dundas Jafine R2OZW / Everbilt R2OHD, EZCNHD) to provide tool-free duct attachment.
Related connections
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