This part is a kind of semiconductor called BTA12.

Function of this product has TRIACS.

Manufacturers : Comset Semiconductors

Image and pinout :

Some of the text within the PDF file :

SEMICONDUCTORS BTA12 Series TRIAC FEATURE Glass passivated triacs in a plastic TO220 package. The bta12 series is suitable for general purpose. They can be used as an ON/OFF function in applications such as static relays,heating regulation, induction motor starting circuits... or for phaseoperation in light dimmers, motorspeed controllers,... Compliance to RoHS. A2 A1 G ABSOLUTE MAXIMUM RATINGS http://www.net/ Symbol VDRM VRRM IT(RMS) ITSM Tstg Tj Ratings Repetitive peak off-state voltage Repetitive peak reverse voltage RMS on-state current Non-repetitive peak on-state current Storage temperature range Operating junction temperature 600 600 Value BTA12-600B BTA12-800B 800 800 12 120 -45 to +150 110 Unit V A A °C °C THERMAL CHARACTERISTICS Symbol R∂j-c R∂j-a R [ ... ]

BTA12 PDF Datasheet Download