HOODDEAL Waterproof Solder Seal Heat Shrink Butt Connectors with Soldering Sleeve 50PCS (Color mixing) Material:An easy one step connection of wires, soldered, insulated and sealed,Material:Tinned Copper Diminishing the chance for corrosion & failure:used in marine, automotive and aviation. Polyolefin tubing in outside and hot melt adhesive in inside Polyolefin heat shrink butt connectors improved pullout strength, provides seal, strain relief, cabl Operating Temperature: -55C to 125C;It fully lived up to my expectations