A QSFP-DD receptacle connector received within a cage includes an insulative housing and a contact module assembly received within the housing. The contact module includes a plurality of horizontal wafers stacked with one another, and each wafer includes an insulator and a plurality of contacts integrally formed therein wherein each contact has a front contact sections extending forwardly into a mating cavity formed in the housing, and a rear connecting section connected to a cable rather than to the printed circuit board. The receptacle connector associated with a cable is attached to a chassis. The cage optionally forms therein two mating spaces respectively receiving two receptacle connectors with the associated cables extending rearwardly.