The shielding element 40 is integrally molded to the tongue portion 12. The limiting portion 121 is accommodated in the second receiving chamber 413. The first docking portion 122 is accommodated in the third receiving chamber 421 surrounded among the two side boards 42 and the at least one sealing board 43. The first docking portion 122 is accommodated in the third receiving chamber 421 surrounded among the two side boards 42 and the two sealing boards 43. The second docking portion 123 is received in the opening 45. The connecting board 44 is molded in a front end of the second docking portion 123. The two limiting ribs 125 are limited in the two limiting slots 422, respectively. The at least one sealing board 43 is attached to a rear of the at least one docking surface 101. A front surface of the second docking portion 123 is flush with front surfaces of the two side boards 42. The two sealing boards 43 are attached to rears of the two opposite docking surfaces 101. The two sealing boards 43 are attached to a top surface and a bottom surface of the first docking portion 122. A front surface of the first docking portion 122 is flush with front surfaces of the two sealing boards 43.