The 40NT120 from Naina Semiconductor is a Silicon Controlled Rectifier with Breakover Voltage 1200 V, Breakover Current 600 to 700 A, Gate Trigger Voltage 3 V, Gate Trigger Current 150 mA, Temperature Operating Range -40 to 130 Degree C. Tags: Screw Mount. More details for 40NT120 can be seen below.