The MMSZ4688 from Micro Commercial Components is a Zener Diode with Zener Voltage 4.7 to 4.935 V, Zener Current 50 mA(zener test current), Voltage Forward 0.95 V, Current Reverse Leakage Current:- 10 uA, Power 500 mW. More details for MMSZ4688 can be seen below.