1、[Safe And Easy To Operate] Solder sealed wire connectors do not need to be crimped, just put the stripped wire into the solder sleeve and heat evenly to complete the connection 2、[Waterproof, Insulation, Non corrosion] Polyolefin tube on the outside, hot melt adhesive and solder on the inside), double wall design ensure perfect insulation and waterproof performance, prevent wire corrosion even in humid environment 3、[Firm And No Slip Lines] The hot melt properties of the inner solder ensure strong tensile strength and tear resistance. The solder melts to hold the wires securely and will never slip out of the connector when heated 4、[Transparent Sleeve, Sufficient Quantity] A total of 200pcs solder heat shrink connectors(50 white, 70 red, 60 blue, and 20 yellow). Specific colors for specific sizes, clear sleeves provide accurate visual inspection during the joining process. Shrinkage ratio for 2:1 5、[Safe And Portable] Solder wire connectors are best for your boat, vehicle, airplane, home and even science projects, ensuring safe and weatherproof soldering. Come with a protective case with compartments for easy storage and portable use