Arlington new 1-piece, screw-in Snap-Tite® connectors for flexible metal conduit are designed for use in new or old work (installed) electrical boxes. Quick and easy installation no Tools. To install in an existing box, pull the conduit through the 3/4 in knockout. Screw the fitting into the cable, then snap the assembly into the box. That's it our retrofit Snap-Tite® connectors accommodate 1/2 in reduced wall flexible metal conduit (RWFMC).