#MBKFD3250 is an OEM Siemens kit. is an original Siemens Main Breaker and Kit and can be used in the lower end of the panel as a Sub Feed Breaker. All branch breaker only go up to 100 amps maximum, so having this option to use up to 250 amps is an exceptional feature by Siemens. Cheapest Price. FXD63B250 type breaker is included in this kit. Some new kits have been panel removed, but all new. Used is also available.