The BZM55C4V7 from Micro Commercial Components is a Zener Diode with Zener Voltage 4.4 to 5 V, Zener Current 1.0 mA, Voltage Forward 1.5 V, Current 5.0 mA, Current Reverse Reverse Leakage Current:- 0.5 - 10 uA. More details for BZM55C4V7 can be seen below.