Cutler-Hammer Breaker Trip Unit, Type KT Thermal Magnetic, Series: C Series, 3 Poles, 125 A, K Breaker Frame, For Use With: Series C DK, KD, KDB, HKD, HKDDC, HKDB, KDC, CKD, CHKD, KG Molded Case Circuit Breaker Frame, Aluminum Terminal, 1-1/4 in H x 3-3/4 in W x 3-1/4 in D