The 2SC4155A from Galaxy Century Microelectronics is a Bipolar Junction Transistor with Emitter Base Voltage 6 V, Base Emitter Saturation Voltage 1 V, Emitter Cut off Current 0.1 µA, Collector Base Voltage 50 V, Collector Cut off Current 0.1 µA. Tags: Surface Mount, NPN Transistor. More details for 2SC4155A can be seen below.