MDN4123LEA, Cutler Hammer, Magnum DS, type MDN, drawout mounted, narrow frame, 3P, 3PH, 1200A, 600V, 42kA@600V, 40°C, bolt-on, complete with interchangeable Digitrip, LI - Long-Time and Instantaneous trip functions, load side lug terminals, solid state, low voltage power insulated case circuit breakers