This part is a kind of semiconductor called FR120N.

Function of this product has IRFR120N.

Manufacturers : Fairchild Semiconductor

Image and pinout :

Some of the text within the PDF file :

IRFR120, IRFU120 Data Sheet January 2002 8.4A, 100V, 0.270 Ohm, N-Channel Power MOSFETs These are N-Channel enhancement mode silicon gate Features • 8.4A, 100V • rDS(ON) = 0.270Ω • Single Pulse Avalanche Energy Rated • SOA is Power Dissipation Limited • Nanosecond Switching Speeds • Linear Transfer Characteristics • High Input Impedance • Related Literature - TB334 “Guidelines for Soldering Surface Mount Components to PC Boards” power field effect transistors. They are advanced power MOSFETs designed, tested, and guaranteed to withstand a specified level of energy in the breakdown avalanche mode of operation. All of these power MOSFETs are designed for applications such as switching regulators, switching convertors, motor drivers, relay drivers, [ ... ]

FR120N PDF Datasheet Download