This is the standard German ignition switch/key assembly. This item was a standard feature in all German aircraft during WWI. It came in two versions – for one magnet (rotary) or two (all inline engines). The pilot was able to select off, 1st magnet, 2nd magnet (for testing during pre-flight) or both (standard setting during flight). The lever was removable but standard across all switches making life for the airfield guards that little bit more interesting but also avoiding the missed dawn patrol due to a lost key.