electrical connector with interlock , including a first part carrying at least one contact and a second part carrying at least one contact , each part having a housing in which the corresponding contact is held . an axially movable locking ring is mounted on the housing of the second part for locking the second part on the first part . the connector includes a retainer that retains the locking ring in the retracted position on the housing of the second connector part , a member for blocking the locking ring in the retracted position at the commencement of the fitting together of the housings of the two parts , a member for eliminating the effect of retaining the locking ring , a member for snap - fastening the two housings one on the other and unblocking the locking ring at the end of the fitting together of the two housings , and a member for locking the two housings in a snap - fastened position as a result of the axial advance of the locking ring .