HOODDEAL 50pcs Waterproof Solder Seal Heat Shrink Butt Connectors with Soldering Sleeve An easy one step connection of wires, soldered, insulated and sealed Can be ideal use in marine and automobile applications Polyolefin tubing in outside and hot melt adhesive in inside Material: Tinned Copper Polyolefin heat shrink butt connectors improved pullout strength, provides seal, strain relief, cab