This part is a kind of semiconductor called ZX120.
Function of this product has Silicon-Power-Z-Diodes (non-planar technology).
Manufacturers : Diotec Semiconductor
Image and pinout :
Some of the text within the PDF file :
ZX 3.9 ... ZX 200 (12.5 W) Silicon-Power-Z-Diodes (non-planar technology) Silizium-Leistungs-Z-Dioden (flächendiffundierte Dioden) 7 Maximum power dissipation Maximale Verlustleistung Nominal Z-voltage – Nominale Z-Spannung Metal case – Metallgehäuse 30 10 12.5 W 3.9…200 V DO-4 5.5 g Ø2 Type Weight approx. – Gewicht ca. Standard polarity: Index R: SW11 M5 10 Cathode to stud / Gewinde Anode to stud / Gewinde (e.g. ZX ...R) Dimensions / Maße in mm Standard packaging: bulk Standard Lieferform: lose im Karton Standard Zener voltage tolerance is graded to the international E 24 (~5%) standard. Other voltage tolerances and higher Zener voltages on request. Die Toleranz der Zener-Spannung ist in der Standard-Ausführung gestuft nach der internationalen Reihe E 24 (~5%). And [ ... ]