The STD9NM50N from STMicroelectronics is a MOSFET with Continous Drain Current 5 A, Drain Source Resistance 730 to 900 Milliohm, Drain Source Breakdown Voltage 500 V, Gate Source Voltage - 25 to 25 V, Gate Source Threshold Voltage 2 to 4 V. Tags: Surface Mount. More details for STD9NM50N can be seen below.