An electrical connector having an insulative housing, a middle grounding member and a pair of contact modules. The insulative housing has a mating portion, a body portion and an upper cavity and a lower cavity at upper and lower sides of the body portion. The mating portion has a top wall, a bottom wall, a pair of side walls and a receiving space therebetween. The middle grounding member is retained in the body portion. Each contact module has an insulator received in the upper or lower cavity, contacts and a locking spring in the insulator. The locking spring is at a lateral side of the contacts and has a fixing portion fixed in the insulator, a locking arm forwardly extending to the receiving space and an extension tab backwardly extending from a rear side of the fixing portion. Each contact has a contact arm extending to the receiving space.