The Ideal wing-nut wire connectors provide an easy, secure grip when connecting a wide range of wires. The specially designed contoured wings make for extra torque and quick work on any electrical job. Combining the two most popular colors of connectors in this class, the Yellow and Red Connectors will cover the widest range of residential applications available in a single package. Live-action spring expands to accept wire shape and size with no pre-twisting required For use with #18 to #8 AWG copper conductors Minimum wire range: 2 #18 AWG, maximum wire range: 4 #10 AWG