An electrical connector includes an insulative housing defining upper and lower rows of passageways arranged in a longitude direction and each of passageway extends along a front-to-back direction perpendicular to said front-to-back direction; upper and lower rows of contacts are assembled into the corresponding upper and lower rows of passageways, respectively; wherein each of said contact has a mating portion folded in half, the mating portion defines a pair of inner faces facing to each other and a pair of outer faces facing away from each other, at least one protruding portion protrudes from one of the inner faces to the other inner face.