The BZM55C39 from Micro Commercial Components is a Zener Diode with Zener Voltage 37 to 41 V, Zener Current 0.5 mA, Voltage Forward 1.5 V, Current 2.5 mA, Current Reverse Reverse Leakage Current:- 0.1 - 5.0 uA. More details for BZM55C39 can be seen below.