The SFF4392GW from Solid State Devices is a Junction Field Effect Transistor (JFET) with Drain Saturation Current 15 to 75 mA, Gate Source Voltage -40 to -57 V, Continous Drain Current 50 mA, Drain Source Resistance 60 Ohm, Gate Reverse Current -130 to -200 nA. Tags: Surface Mount. More details for SFF4392GW can be seen below.