Contact configuration and J7 series fit
The Omron J73KN-C-11S is a 2-pole auxiliary contact block with one normally-open and one normally-closed contact, designed to snap onto the front of Omron J7 series contactors. The contact configuration — 1 N.O. + 1 N.C. — is the most common for feedback and interlock circuits in motor starter applications; the N.C. side typically reports contactor state to a PLC, while the N.O. side enables a holding circuit.