✅Safety Insulation- The wire nuts are made of premium quality plastic shells and metal springs.The nylon shaped shell has thick wall, high hardness and is not easy to aging. Rugged housing withstands extreme environments, up to 221°F (105°C). It can effectively prevent the unstable connection of leakage box and enhance the safety and insulation.UL486C Listed and CSA 22.2 No188 Certified. ✅Good Conductivity- Wire cap contains a high-quality metal coil spring inside to firmly grasp each wire and keep the wires connected stablely. Its strong conductivity increase the current flow while decrease the posibility of the voltage instability. ✅Simple and Practical- The wire nuts assortment kit is easy to operate, just strip off the plastic shell of the wires that need to be connected, twist the wires together, and then screw on the wire connector to connect the wires securely. No need for soldering or electrical tape, spring steel provides a stable connection when you are doing wiring projects, making your wiring work easy. ✅Widely Application- Electrical wire nuts can be used to connect many electrical wiring projects and applications, including home wiring, automobiles,ship wiring, residential and commercial applications etc. Necessity for anyone who does any type of electrical work. ✅Wire Nuts Connectors: The package contains 1500 wire nuts, including 400 x P1 Gray, 400 x P2 Blue, 300 x P3 Orange, 200 x P4 Yellow, 200 x P6 Red.The large quantity is sufficient enough for your daily electrical work. They are suitable for both single hard wire and multi strand wires. SUTETLW Wire Nuts Assortment Kit 1500 PCS Insulating Insert Twist Electrical Wire Connectors Nuts, Springs Screw Terminals Wire Caps for Wire Connection, 5 Sizes Safety Insulation- The wire nuts are made of premium quality plastic shells and metal springs.The nylon shaped shell has thick wall, high hardness and is not easy to aging. Rugged housing withstands extreme environments, up to 221°F (105°C). It can effectively prevent the unstable connection of leakage box and enhance the safety and insulation.UL486C Listed and CSA 22.2 No188 Certified. Good Conductivity- Wire cap contains a high-quality metal coil spring inside to firmly grasp each wire and keep the wires connected stablely. Its strong conductivity increase the current flow while decrease the posibility of the voltage instability. Simple and Practical- The wire nuts assortment kit is easy to operate, just strip off the plastic shell of the wires that need to be connected, twist the wires together, and then screw on the wire connector to connect the wires securely. No need for soldering or electrical tape, spring steel provides a stable connection when you are doing wiring projects, making your wiring work easy.