The STD4NK50Z-1 from STMicroelectronics is a MOSFET with Continous Drain Current 3 A, Drain Source Resistance 2200 to 2700 Milliohm, Drain Source Breakdown Voltage 500 V, Gate Source Voltage -30 to 30 V, Gate Source Threshold Voltage 3 to 4.5 V. Tags: Through Hole. More details for STD4NK50Z-1 can be seen below.