MF1-B-34-615-1-BB6-B-C M 1 Pole Thermal Magnetic Circuit Breaker. Carling Technologies M-Series miniature hydraulic/magnetic circuit breakers ideally designed for demanding applications requiring space saving features. The M series design features a snap-in front panel mounting in a compact, space saving, parallel pole configuration. The circuit breakers feature two uniquely designed terminals that provide the highest level of balanced circuit protection.