3-1 Ratio - shrink to 1/3 of its original diameter, double wall lined with glue inside for a marine grade waterproof seal, with anti stick tape no tacky interior, diameter 3/8 (0.37inch) (9.5 mm), 8 feet long, please see diameter chart(picture 3). Safe & ECO-Friendly - UL Listed for up to 600 voltage -55-125℃ working tempurature which ensures its safe and reliable, RECH/ROHS compliance halogen and lead free protect you and your family. DOUBLE WALL TUBING - Take out the anti-adhesive paper inside then apply heat, adhesive comes out and seals the connection, creating marine grade waterproof insulation, corrosion resistance water & oil proof, VW-1 Flame Retardants, High temperature resistance 3/1 shrinkable glue inside wire. EASY TO USE - Choose the right size you need and simply slide shrinking tubes over your connection point and apply heat around 70-125℃ temperature evenly with a hot air gun. APPLICATIONS - Shrink tube are mainly used for industrial repair, ship, automotive, 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.