Chicago plenum screw in connectors are specifically used with Garvin Industries’ “air tight” Chicago plenum flexible metal conduits. They attach plenum flex conduit to Garvin Chicago plenum boxes and enclosures. Garvin Industries’ Chicago plenum connectors screw in easily to Chicago plenum 3/8" flexible metal conduits and create an "air tight" seal. They must be used with other Garvin Chicago plenum boxes and covers.