An electrical connector (100) in accordance with the present invention is capable of mating with at least one of the first and second complementary connectors. The electrical connector includes a housing (2), a number of first terminals (41) and a pair of second terminals (42). The housing includes an upper wall (21), a lower wall (22) opposite to the upper wall, and a pair of sidewalls (23) connecting with the upper and lower walls. The housing defines a receiving space (20) circumscribed by the upper wall, the lower wall and the sidewalls. The first terminals are assembled to the upper wall, and the second terminals are assembled to corresponding side walls. Each terminal includes a mating portion (40), an intermediate portion (43) engaging with the housing to retain the terminals in the housing and a tail portion (44). The mating portions of the first terminals are exposed to the receiving space and the mating portions of the second terminal are laterally exposed outside the housing.