The MMBZ5250C from Micro Commercial Components is a Zener Diode with Zener Voltage 19.6 to 20.4 V, Zener Current 6.2 to 0.25 mA, Voltage Forward 1.2 V, Current Reverse Leakage Current:- 0.1 uA, Power 300 mW. More details for MMBZ5250C can be seen below.