The 2N4857A from Central Semiconductor is a Junction Field Effect Transistor (JFET) with Drain Saturation Current 20 to 100 mA, Drain Source Resistance 40 Ohm, Gate Current 50 mA, Gate Reverse Current 0.25 nA, Power Dissipation 0.36 W. Tags: Through Hole. More details for 2N4857A can be seen below.