The BZX84C18W from Micro Commercial Components is a Zener Diode with Zener Voltage 16.8 to 19.1 V, Zener Current 5 mA, Voltage Forward 1.2 V, Current 1 mA, Current Reverse Reverse Leakage Current:- 0.1 uA. More details for BZX84C18W can be seen below.