T435-600B-TR.
STMicroelectronics
Price range: $0.71 - $1.37
TRIAC 600V 4A D-PAK; Peak Repetitive Off-State Voltage Vdrm:600V; On State RMS Current IT(rms):4A; Triac Case Style:TO-252; Gate Trigger Current Max (QI) Igt:35mA; Gate Trigger Voltage Max Vgt:1.3V; Peak Gate Power:1W