Trust in secure terminal connections when you use 3M Scotchlok Color-Coded Butt Connectors. These snug-fitting connectors are made of highly conductive electrolytic copper with a tin-plated finish that's non-corrosive. They feature a vinyl-insulated, seamless barrel and withstand temperatures of -40 to 221 degrees F (-40 to 105 degrees C). 3M Butt Connectors are all-around great performers.