cavity 25 the base 2 has a rear wall 230 defining a slot 231 therein in communication with the cavity 25 for receiving a contact module 4 the contact module 4 comprises a number of contacts 41 fixed in a spacer 42 each contact 41 has a mounting end section 412 and a mating end section 411 respectively extending beyond opposite faces of the spacer 42 the spacer 42 is inserted into the slot 231 and has a rib 421 engaging with an edge of an inner face of the cavity 25 for retaining the spacer 42 in the slot 231 the mating end sections 411 of the contacts 41 extend through the cavity 25 and are received in the channels 251 the mating end sections 411 form an arcuate portion for engaging with contacts not shown of a mating plug connector 6 fig4 a and 4b the base 2 defines a pair of pivot holes 24 therein exposed to opposite side faces 20 of the base 2 each side face 21 also has a projection 26 formed thereon a cover 3 comprises two spaced side walls 30 defining an interior space 31 therebetween each side wall 30 has an inside face 301 on which a trunnion 321 is formed extending into the interior space 31 the trunnions 321 are received in the corresponding pivot holes 24 of the base 2 thereby rendering the cover 3pivotable about the trunnions 321 with respect to the base 2 between a closed position fig3 a and an open position fig3 b the cover 3 may be provided with grooves 34 on an outer surface thereof for facilitating the manual pivotal movement of the.