The NTE5558 from NTE Electronics is a Silicon Controlled Rectifier with Breakover Voltage 800 V, Breakover Current 300 A, Gate Trigger Voltage 1 to 1.5 V, Gate Trigger Current 0.25 to 0.075 A, Temperature Operating Range -40 to 125 Degree C. Tags: Through Hole. More details for NTE5558 can be seen below.