Abstract: An electrical connector assembly includes a male connector and a female connector. The male connector comprises an insulative housing, a plurality of silos projecting from the housing, a plurality of contacts received in the silos, a guiding arm formed on a top surface of the housing and a pair of fixing bars extending from distal ends of the housing. The female connector has an insulative housing, a plurality of receptacles formed in the housing for engaging with the corresponding silos, an engaging slot formed in a top surface of the housing, and a plurality of terminals received in the receptacles for electrically contacting the corresponding terminals of the male connector. In assembly, the guiding arm of the male connector is inserted into the engaging slot of the female connector for guiding the connectors and preventing improper engagement therebetween. The silos and the receptacles are manufactured with the same rectangular cross-section thereby reducing production costs.