A registered jack (RJ) consists of the jack construction and wiring pattern of a standardized physical network interface to connect telecommunications or data equipment to a service provided by local exchange carrier or long distance carrier. Many CyberPower surge protectors feature data protection for RJ-11 (standard phone lines) and RJ-45 (Ethernet).
RJ-11 (RJ11): A telephone interface, a RJ-11 (registered jack-11), also known as RJ11, uses a cable of twisted wire pairs and a modular jack with two, four, or six contacts. A four-wire RJ-11 connector (6P4C) plugs a telephone into the wall and the handset into the telephone. A six-wire RJ-11 (6P6C) connector is commonly used with three telephone lines.
RJ-45 (RJ45): A data networking interface, the eight-wire RJ-45 (registered jack-45), also known as RJ45, uses a cable of twisted wire pairs and an 8-pin modular jack. RJ-45 connectors are typically used with Ethernet and Type 3 Token Ring networks.