How it connects
The externally threaded barrel body with two opposing flat sides is inserted through a panel knockout and clamped firmly to the panel by tightening a thin hex mounting nut over the male threads against the rear of the panel.
Male and female halves
Male externally threaded barrel on the lock body that mates with a matching female threaded panel mounting hex nut.
Usually connects to
- Matching double-D panel opening, or a round hole with compatible anti-rotation plate
- Matching internal-thread retaining hex nut
- Compatible mailbox mounting clip
Common sizes
- Common double-D mounting bodies are about 3/4 in (19 mm) OD with 5/8 in (15.9–16 mm) flats; thread descriptions include 3/4-24 and 3/4-27 UNS/UNEF.
- Body lengths include 5/8, 13/16, 7/8 and 1-1/8 in. A reported 16.5 mm AF and 5/16 in panel capacity are estimates; confirm the particular barrel and thread.
Where it is used
residential and commercial mailboxescluster box units (CBU)sheet metal cabinet doorspostal lockersCabinet door locksDrawer locks
Variations
- threaded barrel with hex nut mount
- grooved barrel with spring clip mount
How to recognise it
Recognised by a cylindrical lock housing with machine threads on the curved surfaces, two parallel flat sides preventing rotation in a double-D hole, and a large-diameter thin hex nut that threads directly onto the housing body.
Often confused with
| Confused with | How to tell them apart |
|---|---|
| Spring clip mailbox cam lock mount | Spring clip mounts use external retention grooves on an unthreaded or partially slotted body and secure with a horseshoe spring clip instead of male threads and a hex nut. |
| Cam-and-groove hose coupling (camlock) | This is a key-operated lock body mounted through a panel, rather than a hose coupling with a groove and locking arms. |
| Universal 3/4 inch threaded fitting | Barrel diameter alone does not establish thread compatibility; verify pitch, profile, flats and retaining nut for the lock model. |
Also called
cam lock threaded barrel mountthreaded mailbox cylinder mountthreaded cam lock bodydouble D threaded lock mountDouble-D cam-lock panel mount
Good to know
Many standard North American mailbox replacement locks (e.g. replacing Auth-Florence, Bommer, Cutler, Miami-Carey) use this standard 3/4 in threaded double-D body style, often supplied with both a hex nut and an optional spring clip.
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