Safety and Environmental Protection: Purple-fox heat-shrinkable tubes are UL and CSA certified, RoHS compliant, free of formaldehyde (HCHO), heavy metals and other harmful substances protecting you and your family from toxins | Versatile and DIY Helper: High-quality heat shrink tubing, they can be used for solder joint protection, group of lines marking, resistance electric capacity reason protection etc. Note: Make sure temperature of your heat gun is up to 212℉(Fahrenheit), then glue inside will soften and seal the connection. | Great Advantages : Our heat-shrinkable tube are with glue lined which has the advantages of good electrical insulation, good sealing, corrosion resistance and high temperature resistance. Anti-aging, tough, not easy to break. | Easy and fast: It is 3:1 heat shrink ratio, and will shrink up to 1/3 of original, only use a lighter heating if the tube is small or hair dryer heating or heat gun for large one. | Widely Applications: Heat-shrinkable tubes are mainly used for wire links, anti-rust and anti-corrosion protection of solder joints, and audio and electrical DIY. Wire ends, harnesses, electronics protection and insulation treatment. Fitness equipment parts and steel structure surface protection and so on.