The BT136 Transistor is TRIAC with 4A maximum terminal current. The gate threshold voltage of the BT136 is also very less so can be driven by digital circuits. Since TRIACs are bi-directional switching devices they are commonly used for switching AC applications. So if you looking to switch control (dim, speed control) an AC load that consumes less than 6A with a digital device like microcontroller or microprocessor then BT136 might be the right for you.
Manufacturer Part No:
Technical Datasheet: BT136-600D Datasheet