The JX040K from Surge Components is a Silicon Controlled Rectifier with Breakover Voltage 600 V, Breakover Current 30 A, Gate Trigger Voltage 0.6 to 0.8 V, Gate Trigger Current 50 to 200 µA, Temperature Operating Range -40 to 110 Degree C. Tags: Surface Mount. More details for JX040K can be seen below.