1.【Marine Grade Wire Connectors】 - The heat shrink connectors kit includes ring, fork, spade, and heat shrink butt connectors. The quality wire connectors make work easier. 2.【Red Copper Tinned】- High-quality red copper effectively prevents copper layer rust and then cause bad contact,anti oxidation prevent electrical sparks. It provides minimal voltage drop, high current flow and less heat. These will prevent short circuits and and make your connection projects safer and better. 3.Durability & Safety】- The polyolefin heat shrink tubing provides the high tensile strength and resistance to stretch and minimize mechanical damage, so there's no worry of rat chewing or similar physical damage issues. The thick tinned copper and seamless barrel design ensures strong and secure crimping all the time with no issues of wire coming off. 4.Waterproof & Flame-retardant】- Insulation tubing features a unique dual-walled design. Adhesive lined inside the 3:1 heat shrink connector will exude hot melt adhesive when evenly heated, shrinks quickly and adheres to wire insulation, which ensure 360 degree secure seal and excellent waterproof property. 5. Insulated waterproof marine grade crimp terminals can be used underground.