Electrical connectors for interconnecting circuit boards. One such connector includes an integral flange for mounting a guidance pin in any of multiple orientations. A corresponding keying block may have a polarization component that can be mounted in a corresponding number of positions. The connector can accept conductive elements with different shapes for signals and grounds, but the housing may be adapted to receive either type of contact in any contact location. Protection of contact elements from excessive yield is provided within the insulative housing of the backplane connector. On the daughter card connector, height difference between ground and signal contacts in wafer assemblies protects components from electrostatic discharge.