An electrical connector includes: an insulative housing defining a front mating cavity; a mating tongue extending into the front mating cavity and defining thereon first and second mating faces opposite to each other, said mating tongue dividing said mating cavity into a first mating space confronting the first mating face for mating with a first complementary connector, and a second mating space confronting the second mating face for mutually exclusively mating with second and third complementary connector; a plurality of first type contacts disposed on the first mating face for connecting with the first complementary connector, a plurality of second type contacts disposed on the second mating face for connecting with the second complementary connector, and a plurality of third type contacts located between the first type contacts and the second type contacts with front ends of the third type contacts exposed to the second mating space.