An electrical connector includes an insulating housing (1) having four side walls interconnecting with each other and defining a receiving space (10) therein. Only one of the side walls defines a plurality of terminal grooves therein and a plurality of terminals (22) are mounted in said terminal grooves. A metallic shell (4) covers on the insulating housing and said shell (4) has a first resilient arm (431) extending in a first direction with a first contacting portion (4311) bending outwardly, and a second resilient arm (432) extending in a reverse direction toward the first resilient arm with a second contacting portion (4321) bending outwardly. The first and second resilient arms (431, 432) space away from each other in a transverse direction perpendicular to said first direction, and said first and second contacting portions (4311, 4321) offset with each other in said first direction.