Package Includes: 1000 blue 16-14 AWG heat shrink butt connectors are suitable for industrial, automotive, marine, electrical and electronics wiring with an operating temperature of -60℉ to 260℉ and min shrink temperature 175℉, meeting daily needs. Tinned Copper Core: Made of thickened 99.9% tinned-copper cores, heat shrink wire connectors combine marine-grade polyolefin heat shrink tubing with adhesive-lined double-insulated tubing. Thick copper can low voltage drop, support high current with low heat, ensuring strong crimp and excellent conductivity to reduce short circuits. Easy, Solder-Free Use: Strip wire insulation, insert into connector, crimp with pliers and heat it evenly with a heat gun in seconds. Butt connectors heat shrink tubing with wire gauge markings are easy to identify and transparent tubing makes inspection easier. 3:1 Shrink Ratio: The hot melt adhesive forms an all-around IP67 waterproof and corrosion-restricted seal. Double-insulated tube is flame-retardant and marine-grade butt connectors support underground use. Secure to Last: Polyolefin tubing of wire connectors provides high tensile strength to resist mechanical damage and external abrasion. Seamless tube barrel and thick tinned copper make connection secure and reliable. Package Includes: 1000 blue 16-14 AWG heat shrink butt connectors are suitable for industrial, automotive, marine, electrical and electronics wiring with an operating temperature of -60℉ to 260℉ and min shrink temperature 175℉, meeting daily needs.