2nd World War Nazi Germany Luftwaffe Flak kampf abzeichen with the unusual marking of L/11 whilst the badge features and reverse hardward set up (see hinge and catch photos) are consistent with those of a different maker / manufacturer.
Obverse of luftwaffe Flak L/11
Manufacturer mark L/11
Detail Eagle LW Flak L/11, Note the fine details in the feathers.
Flak cannon Structure and detail. Note the clarity and number of bolts / rivets.
Luftwaffe Flak hinge arrangement. Be sure to check that the Reverse hardware set up is consistent with that of the badge manufacturer from the Obverse. Whilst not always the case, the presence of a strange / unfamiliar reverse with a known Obverse should be enough to start asking questions regarding originality.
Side on view of the hinge, not the greatest photo of the badge but enough detail for reference / comparison purposes.
Catch plate of flak badge, as with the hinge, soldered directly onto the rear of the badge.