who knows what that is?

Intrusion lock RX for beard key

RX – Key backup –

Intrusion protection for beard keys:

To arrears the securing curved nose into the door key. To solve the fuse simply pull the hook down.

stainless steel height 85 mm with spring in clear box

also prevents the door keys from being lost, or Children's Way

Note: Doors with beard keys provide only little security against burglary.

These doors should be converted to modern lock cylinders

(and attach safety fitting). Source