The crystal head is mainly composed of two parts: plug shell + gold piece. The crystal head can be divided into two types: network crystal head and telephone crystal head. Network crystal heads include super five types of unshielded / shielded crystal heads, and six types of unshielded / shielded crystal heads. The network crystal head is used for data transmission and other interfaces, and the telephone crystal head is used for voice transmission and other interfaces. It is suitable for terminating on-site and connecting cables to realize the connection between equipment, jumper racks, and modules.