FCI Basics Latch-N-Lok is a shielded, latching input/output connector with PCB receptacles and cable plug kits for signal, power, grounding, and shielding applications. Latch-N-Lok connector produces an audible ‘click’ sound when it is properly connected, indicating that the IO is ready to function. The cable connectors accommodate a wide variety of cable diameters and wires ranging from 32-20AWG.