The BT300S-600R from WeEN Semiconductors is a Silicon Controlled Rectifier with Breakover Voltage 600 V, Breakover Current 65 A, Gate Trigger Voltage 0.25 to 1.5 V, Gate Trigger Current 0.015 A, Temperature Operating Range -40 to 150 Degree C. Tags: Surface Mount. More details for BT300S-600R can be seen below.