Referring to FIG. 1 and FIG. 2, the tongue portion 12 has a limiting portion 121, and a docking portion 120 protruded frontward from a middle of a front surface of the limiting portion 121. The docking portion 120 has a first docking portion 122 protruded frontward from the middle of the front surface of the limiting portion 121, and a second docking portion 123 protruded frontward from a middle of a front surface of the first docking portion 122. The docking portion 120 of the tongue portion 12 of the insulating housing 10 has at least one docking surface 101 for being docked with the docking connector. The tongue portion 12 opens a plurality of terminal grooves 124 extending and penetrating through a rear surface of the tongue portion 12 along the longitudinal direction, and penetrating through a front of the at least one docking surface 101 along a vertical direction. The vertical direction is defined as a direction perpendicular to both the longitudinal direction and the transverse direction. The plurality of the terminal grooves 124 are transversely arranged along the at least one docking surface 101.