DNC is made of highly weather-resistant Silicone rubber material. The product and construction quality are improved through the dual-layer design of the built-in rubber ring. It is widely used in various types of cable joint protection for coaxial cables, jumpers, DIN connectors, connectors, and N-type connectors in communication base stations. The simple and convenient operation method allows to quick construction without the use of tools in narrow spaces where fire sources are not allowed. The new adhesion ring structure of the inner layer can improve the hardening issues of traditional mastic, and make the protection ability of waterproof insulation and sealing more reliable and durable.