An electrical interconnection system comprising one or more insulative projecting members. The electrical interconnection system may comprise a first connector and a second connector. Each connector may comprise one or more projecting members extending along the mating direction. When the connectors are mated, the projecting member(s) may be configured to affect the impedance of the signal conductors of the connectors. In a partially mated position, the projecting member(s) may be configured to fill at least a portion of the region separating the connectors, thereby replacing air that might otherwise exist in that separation with a dielectric member. Because this dielectric constant is closer to what would be experienced in the fully mated position, the magnitude of the change in impedance as a result of separation may be less than had the entire space been filled with air.