An electrical connector includes an insulating housing having a pair of side-walls, a plurality of terminals retained in the insulating housing and comprising contacting portions and a shielding shell surrounding the housing. Each of the side walls of the housing defines a window portion thereof to communicating with the mating cavity and an exterior. A pair of side walls of the shell covers on the side walls of the insulating housing and each defines a resilient arm extending into the mating cavity through the window portion.