The RM4N500LD from Rectron Semiconductor is a MOSFET with Continous Drain Current 4 A, Drain Source Resistance 1100 to 1500 milliohm, Drain Source Breakdown Voltage 500 V, Gate Source Voltage -30 to 30 V, Gate Source Threshold Voltage 3 to 4 V. Tags: Surface Mount. More details for RM4N500LD can be seen below.