a housing formed of a base frame and a cover, said housing having an accommodation chamber defined within said base frame and said cover, a first opening for the insertion of a HDMI (high definition multimedia interface) plug and a second opening for the insertion of at least one RJ-type plug; and

an electric module mounted in said accommodation chamber inside said housing, said electric module comprising a circuit board, a HDMI (high definition multimedia interface) jack mounted on said circuit board and abutted against said first opening of said housing for receiving a HDMI plug of a HDMI cable, and at least one RJ-type jack mounted on said circuit board for signal transmission with said HDMI jack and abutted against said second opening of said housing for receiving a RJ-type plug of a RJ-type transmission cable respectively.