What kind of info are you after? The FF series was a bog-standard mag from ca. 1927 up to the middle of the 30's, like the BTH MD. Could dig some cataloge pages in German, but that might not be too helpful.
Hi, Alex i have a thread in the motoclub.de forum ( in deutscher Sprache) for your mag and mine. (perhaps you can see in: allgemeine Vorkriegsmotorräder, Bosch Zündmagnet FF1........) I hope that anyone can help us. If i know something, i will tell you.