The Siemens MBK125 is a Molded Case Circuit Breaker. This type MBK circuit breaker is a member of The MBK Series family. The MBK125 is a 2 pole, 240 Volt, 125 amp rated circuit breaker, with an AIC rating of 22kA@240V. The MBK125 is manufactured by Siemens. The MBK125 uses a Plug-In connection. Includes Thermal Magnetic protection.