The BZT52B18JS from Micro Commercial Components is a Zener Diode with Zener Voltage 17.64 to 18.36 V, Zener Current 1.00 mA, Voltage Forward 0.9 V, Current 5.0 mA, Current Reverse Reverse Leakage Current:- 0.1 uA. More details for BZT52B18JS can be seen below.