The MMBZ5248C from Micro Commercial Components is a Zener Diode with Zener Voltage 17.64 to 18.36 V, Zener Current 7 to 0.25 mA, Voltage Forward 1.2 V, Current Reverse Leakage Current:- 0.1 uA, Power 300 mW. More details for MMBZ5248C can be seen below.