Abstract: An electrical contact element (ECE) for a plug connector includes a metal flat contact plug and a plastic body. The plastic body has a plug tip disposed on an insertion-side end face of the flat contact plug. The plug tip has a cross-sectional area including two undulated edge contours which extend symmetrically or asymmetrically with respect to a center axis of the cross-sectional area. A cross-sectional width between the edge contours varies continuously along the plug tip and has a local maximum(s) outside of end regions of the plug tip. The plug connector may include a mating contact element (MCE) having contact slats which contact the edge contours of the plug tip as the ECE is partially inserted along an insertion direction into the MCE and contact the contact surfaces of the flat contact plug as the ECE is fully inserted along the insertion direction into the MCE.