An electrical connector (300) includes a number of wafers (30) and each wafer including an insulative housing (31) and a number of contacts (32). The housing defines a mating surface (311) and a mounting surface (312), and a plurality of passages (313) concaved from the mounting surface. The housing has a platform (314) formed in each passage and two cavities (315) defined on opposite sides of the platform. The platform has a pair of protruding portions (316) disposed above the cavities respectively. Each cavity has an opening (317) defined in the mounting surface. The contacts are received in the passages of the insulative housing. Each contact includes a receptacle (321) formed with a pair of legs (324). Each leg has a preloaded portion (325). The preloaded portion is insertable into the cavity via the opening along a mounting direction perpendicular to the mounting surface while spreading out the legs.