The STL3NK40 from STMicroelectronics is a MOSFET with Continous Drain Current 0.43 A, Drain Source Resistance 4500 to 5500 Milliohm, Drain Source Breakdown Voltage 400 V, Gate Source Voltage - 20 to 20 V, Gate Source Threshold Voltage 0.8 to 2 V. Tags: Surface Mount. More details for STL3NK40 can be seen below.