A connector assembly (10) includes a lower housing (14) and an upper housing (12) each generally including the basic structure of the typical SO DIMM connector housing (16, 16'). Each housing (14, 12) defines two rows of passageways (20, 20') on two sides of the central slot (18, 18') in which the corresponding module (100) is received. A plurality of contacts (40, 42, 50, 52) are received within the corresponding passageways (20, 20') wherein the tail of each contact (40, 42, 50, 52) extends downward to engage the corresponding circuit on the PC board (100) on which the connector assembly (10) is mounted. The upper housing (12) includes a standoff portion (30) thereabouts wherein the standoff's thickness is generally equal to the thickness of the lower housing (14) so that the upper housing (12) defines a space (32) thereunder to have the lower housing (14) positioned therein under the condition that the upper housing (12) and lower housing (14) are substantially offset with each other in the front-to-end direction.