3M™ Scotchlok™ Color-Coded Closed-End Connector is an electrical crimp sleeve connector with a copper insert that allows fast work of splicing copper conductors. The connector is nylon-insulated, and is 600V-rated for building wire and 1000V-rated for signs, fixtures or luminaires. It withstands temperatures of -40 to 221 degrees F (-40 to 105 degrees C).