An electrical connector socket includes an insulative housing forming a plurality of passageways extending through the opposite top and bottom surfaces of the housing. A plurality of contacts are disposed in the corresponding passageways, respectively. Each of the contacts includes opposite upper and lower contacting sections extending beyond the top surface and the bottom surface respectively. First and second upper posts extend upwardly from the top surface around two opposite corners and are different and spaced from each other diagonally. First and second lower posts extend downward from the bottom surface around the same two opposite corners and are different and spaced from each other diagonally.