Siemens main breaker kits are used as a replacement main breaker in Siemens type EQ load centers. Type EQ load centers were produced prior to 2002. Check the load center wiring diagram for confirmation, the MBK200 is the equivalent to the EQ9685.
Main breaker conversion kit
Designed to allow for convertibility and invertiblilty of your panel
Straight-in wired design reduces wire cost
Converts main lug load centers to main breaker load centers