Cupchain connector was designed specifically to accommodate 4mm cupchain. Simply add a dab of glue to secure, place cupchain in connector, push down then bend 2 prongs over with pliers. Connector can also fit other types of cube beads smaller than 4mm in size.
Chain Terminator>Silver Plated/Finished>Silver ColoredFindings and Components>Terminators>Chain TerminatorSilver Plated/FinishedSilver Coloredhttp://www.firemountaingems.com/itemdetails/h20a6175fnH20A6175FNConnector, silver-finished brass, 4.5x4.5mm, fits 4mm cupchain. Sold per pkg of 50.//image3.fmgstatic.com/images/pa6175fnb.jpg5.845.84As Low As $0.05 per connector