PDF datasheet with the document code DS9045-05, a 175 KB file whose name gives no device, part number or manufacturer, so open it to see which component it covers.

Datasheet for the 2SK2043 N-channel MOSFET, with the file name stating a 600 V drain-source rating and 2 A drain current.

Datasheet PDF whose name, K3918, most likely refers to a component marking; it may be a power MOSFET, but that cannot be confirmed from the name, so open the file to see…