The G4N50J from Goford Semiconductor is a MOSFET with Continous Drain Current 4 A, Drain Source Resistance 2000 to 2300 milliohm, Drain Source Breakdown Voltage 500 V, Gate Source Voltage -30 to 30 V, Gate Source Threshold Voltage 3 to 4 V. Tags: Through Hole. More details for G4N50J can be seen below.