Siemens MBK200A 200-Amp Main Circuit Breaker for Use in Ultimate Type Load Centers
SIEMENS main breaker kits are used to convert the Ultimate type of main lug load centers to main breaker load centers, or can be used as a replacement main breaker in main breaker type Ultimate load centers.  Ultimate load centers are the current load center in production and went into production in 2002.  Check the load center wiring diagram for confirmation.