The SFT5666/39 from Solid State Devices is a Bipolar Junction Transistor with Emitter Base Voltage 6 V, Base Emitter Saturation Voltage 1.2 to 1.5 V, Emitter Cut off Current 1 µA, Collector Base Voltage 200 V, Collector Cut off Current 10 µA. Tags: Through Hole, NPN Transistor. More details for SFT5666/39 can be seen below.