The STD5N65M6 from STMicroelectronics is a MOSFET with Continous Drain Current 4 A, Drain Source Resistance 1150 to 1300 Milliohm, Drain Source Breakdown Voltage 650 V, Gate Source Voltage - 25 to 25 V, Gate Source Threshold Voltage 2.25 to 3.75 V. Tags: Surface Mount. More details for STD5N65M6 can be seen below.