Abus CFA 1000 Operating Instructions Manual page 50

Attention!
The cylinder lock has to have an emergency operation feature.
That means that the cylinder lock can be opened from the outside independent
of whether a key is inserted on the inside or not.
With "normal" cylinder locks, the key inserted on the inside will block opening
from the outside. The door can no longer be opened from the outside!
If the batteries of the door lock actuator are flat or in case of a defect, the door
can then only be opened with force! Access to the flat is then blocked!
Cylinder locks with emergency operating features are as a rule only to be obtained from a
specialist shop, possibly in a well-stocked building centre.
If your flat has a second entrance, (and, of course, you always have a key at hand), in individual
cases a conventional "normal" cylinder key can be used (unlocking from the outside with a key
is then normally not possible!).
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Tip:
If you wish to keep your key and wish to/can use the existing "old" cylinder lock, for
example, on the back door (advantage: only one key for all doors), then hand in your
key or the security card when buying a new cylinder lock to the retail shop to receive
the matching cylinder lock for this key (depending on type of the cylinder lock, possibly
not possible).
If you are not sure whether a cylinder lock has an emergency operation feature or not,
simply insert a key from each side into the cylinder lock and test the feature on both
sides of the cylinder lock.
If you are in doubt, please consult a specialist.
If dimensions are stated on the packaging with "80mm (35/45)", the total length of the
cylinder lock is "80mm", the external dimension "35mm" and the internal dimension
"45mm".
Subsequent measuring or keeping the purchase docket could be sensible, however.
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