Manufacturers designed it so you can apply:
Lock-specific oil
Graphite spray
WD-40 (in emergencies)
directly into the lock’s inner pins and springs.
By applying lubricant through this hole, you can often:
Free a stuck key
Loosen a jammed mechanism
Restore smooth key movement
Prevent long-term wear
Most people spray lubricant on the key or keyhole—but the drainage hole is actually the most effective spot.
3. It Helps Maintain Air Pressure Inside the Lock
This is a less-known reason, but still useful.
When the lock is opened or closed, tiny pressure changes occur inside the mechanism.
This little hole helps:
Equalize internal pressure
Prevent vacuum-locking
Avoid internal suction that can jam the device
In short:
It keeps the lock working smoother for longer.
Why Manufacturers Don’t Advertise This Feature
The simple answer?
Most people never ask.
