The T161-125-18 from Proton-Electrotex JSC is a Silicon Controlled Rectifier with Breakover Voltage 1800 V, Breakover Current 4.0 to 4.5 kA, Gate Trigger Voltage 1.50 to 3.00 V, Gate Trigger Current 150 to 400 mA, Temperature Operating Range -60 to 125 Degree C. Tags: Stud Mount. More details for T161-125-18 can be seen below.