Melt PET film water blocking tape is a type of cable accessory used in telecommunication and power cables. It is designed to prevent water from entering the cable core and damaging the cable components. The tape is made of a melt PET (polyethylene terephthalate) film that is coated with a water blocking compound. When the tape is applied to the cable, the heat generated during cable production or installation melts the PET film and activates the water-blocking compound, creating a water-tight barrier. The tape is typically used in conjunction with other water-blocking materials such as filling compounds and swelling tapes to provide comprehensive water protection for the cable.