An electrical connector (100) provides an interface for storage device. The electrical connector (100) includes an insulated housing (10) and a number of electrical contacts (S1-S7, P1-P9) disposed in the insulated housing (10). The insulated housing (10) defines a slot (16) for receiving a integral tongue portion (26) of a mating electrical connector (200). The number of electrical contacts (S1-S7, P1-P9) are lined along an inner side face (167) of the slot (16) for mating with the mating electrical connector (200). The first inner side face (167) of said slot (16) defines two grooves (166, 168) for polarizing the mating electrical connector (200) and the internal micro Serial ATA plug connector from other Serial ATA cables.