Industrial Circuit Breakers, Three Pole, 125-600A Circuit Breakers, Thermal-Magnetic Trip, J600 Line Circuit Breakers. Types TJK, THJK . Interchangeable Trip, includes Cu/Al Line and Load Lugs, not suitable for reverse feed. Trip Unit Only. Use with Standard and Hi-Break Frames. TJK 400-AMP FRAME 3-POLE TRIP UNIT