The SSM3K43FS from Toshiba is a MOSFET with Continous Drain Current 0.5 A, Drain Source Resistance 460 to 1520 Milliohm, Drain Source Breakdown Voltage 20 V, Gate Source Voltage -10 to 10 V, Gate Source Threshold Voltage 0.35 to 1 V. Tags: Surface Mount. More details for SSM3K43FS can be seen below.