NEF Electrical Butt Connectors, Blue Heat Shrink Solder, 16-14 Gauge, 25 Pack 16-14 AWG Blue Heat Shrink Solder Electrical Butt Connectors - 25 piece set Translucent, adhesive-lined polyolefin tubing allows visual inspection, prevents wire corrosion, and provides a waterproof seal. Easy installation with pre-measured solder takes the guesswork out of the soldering process. A soldered electrical connection provides superior current flow and tensile strength. Color-coded tubing with wire gauge imprint provides easy identification of the correct part for the job