The BZT55C4V7 from Micro Commercial Components is a Zener Diode with Zener Voltage 4.4 to 5.0 V, Zener Current 1 mA, Voltage Forward 1.5 V, Current 5 mA, Current Reverse Reverse Leakage Current:- <0.5 - <10 uA. More details for BZT55C4V7 can be seen below.