The 2SK433B from Isahaya Electronics is a Junction Field Effect Transistor (JFET) with Drain Saturation Current 0.6 to 1.5 mA, Gate Source Voltage -50 V, Forward Transfer Admittance 1.0 to 3.0 mS, Continous Drain Current 0.6 to 12 mA, Drain Source Resistance 250 Ohm. Tags: Surface Mount. More details for 2SK433B can be seen below.