The ABB 1SFN035203R1000 is a contactor accessory designed for use with the AF116–AF205, AF190–205, and AF265–AF370 contactor frames. This is the part that mounts to or interfaces with those contactors — a spare or replacement component for a panel already built around those ABB frame sizes.
The accessory is sized for the AF116 through AF370 frame family. If your panel was specified with an ABB AF116, AF190, AF205, or AF265 contactor, this is the matching accessory. Verify the specific interface — mechanical interlock, auxiliary contact block, or coil interface — against the existing contactor's mounting profile.