An electrical connector (100) includes an insulative body (1) having a wide tongue (123) and a narrow tongue (121) split by a gap (124) therebetween. A metallic shell (32) includes a front pocket (320) defining a large receiving cavity (327) enclosing the wide tongue (123), a small receiving cavity (325) enclosing the narrow tongue (121), and a non-circumferentially enclosed notch structure (33) which protrudes into the gap (124) so as to form the large receiving cavity (327) and the small receiving cavity (325). Besides, the notch structure (33) defines a notch (330) opened to an exterior from a bottom side thereof. First and second sets of contacts (211, 212) are located in the wide tongue and the narrow tongue, respectively, and the first contacts (211) are compatible to version 2.0 Micro Universal Serial Bus.