The FDS4559_F085 from onsemi is a MOSFET with Continous Drain Current -3.5 to 4.5 A, Drain Source Resistance 55 to 105 milliohm, Drain Source Breakdown Voltage -60 to 60 V, Gate Source Voltage -20 to 20 V, Gate Source Threshold Voltage -3 to 3 V. Tags: Surface Mount. More details for FDS4559_F085 can be seen below.