An electrical connector includes an insulative housing having a mating face, a mounting face, a pair of side walls, a elongated central slot recessed downwardly from the mating face, a first end wall and a second end wall, the central slot being positioned between the side walls, the first end wall and the second end wall, the side walls include a plurality of passageways communicating with the central slot; a plurality of contacts being retained in the passageways respectively and protruding into the central slot; a metal board lock extending downwardly through the first end wall and being attached to the first end wall; a retainer attached to the first end wall to mating with a corresponding card; the board lock is sandwiched between the retainer and the first end wall.