The BZT52B20JS from Micro Commercial Components is a Zener Diode with Zener Voltage 19.60 to 20.40 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 BZT52B20JS can be seen below.