This part is a kind of semiconductor called K4208.

Function of this product has Silicon N-channel enhancement MOS FET.

Manufacturers : Panasonic

Image and pinout :

Some of the text within the PDF file :

Plehtatsp:e/M/vaiiwsniwttefw.nolsalenocmwiie/cnpolDgdiina.ssUncpceRoaodLnnnttiapidalinmsnbasuaouiocneneniuoetdtdcnd.ieltticnnaytnmocalp.eujaniuesepctn/ddtieeetentsnfyn/yfopaproelnelmdcoaetwitioynnpg.efourDisMcaionnttieProductnnulifecycleaenstage.dce/ Power MOS FETs This product complies with the RoHS Directive (EU 2002/95/EC). 2SK4208 Silicon N-channel enhancement MOS FET For high speed switching circuits  Features  Gate-source surrender voltage VGSS : ±30 V guaranteed  Avalanche energy capability guaranteed: EAS > 801 mJ  High-speed switching: tf = 88 ns (typ.)  Absolute Maximum Ratings TC = 25°C Parameter Symbol Rating Unit Drain-source surrender voltage Gate-source surrender voltage Drain current Peak drain current * Avalanche energy capability VDSS VGSS ID [ ... ]

K4208 PDF Datasheet Download