Note that the key number of an Ahrend B key consists of a letter with 4 numbers.
The number of the key can be found on the key itself or on the lock.
If it is not clear which brand of lock it is, you can take a photo of the lock up close.
We need to be able to see the entrance to the lock well to be able to identify the brand.
You can email the photo to firstname.lastname@example.org or via WhatsApp to 06-20649337