LYNN KEY-CAT6-COUPLER-BK (Millennium part 521009) is a black RJ45-to-RJ45 keystone coupler that joins two patch cords or extends an existing run without re-terminating either end. The keystone body mounts in faceplates, surface boxes and patch panels, so a coupled through-connection looks as finished as a punched-down jack. CAT6-rated contacts maintain pair geometry to keep crosstalk and return loss within spec for Gigabit and short-reach 10GBASE-T. Useful for camera and access-point drops, temporary extensions and troubleshooting, where a technician needs a clean pass-through rather than a field-crimped plug.