The LA9FJ4H4F is a mechanical interlock from the TeSys F range, designed to physically prevent two or three contactors from closing simultaneously. It's a safety interlock, not an electrical one — the bar sits between the contactors and blocks their armatures if one is already pulled in. This version mounts in a 3-vertical stack and interlocks bottom contactors LC1F115...LC1F150 (3P or 4P) or CR1F150 (3P or 4P), middle LC1F265...LC1F330 (3P or 4P) or CR1F265 (3P or 4P), and top LC1F400 (2P, 3P, or 4P) or CR1F400 (3P or 4P). If you're running a reversing starter or a two-speed motor starter with these F-frame contactors, this is the mechanical tie-bar that keeps the power circuit from welding closed.
Mounts vertically on the contactor stack — three units, one per pair. No DIN-rail footprint; it clips onto the contactor's own mounting tabs. The interlock bar is mechanical only, so no wiring, no coil suppression, no auxiliary contact to land. Just snap it on and verify the armature movement before powering up.