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1. A fastener, comprising: a head and a shank having a central longitudinal axis, wherein the head is constructed including a recess having a central portion and a plurality of wings radiating outwardly from the central portion, each of the wings having driving surfaces including an installation driving surface and a removal driving surface, separated by a non-driving transition contour, the non-driving transition contour forming a radially inward-most portion of the wing, and wherein the driving surfaces are constructed in substantially parallel alignment with the central longitudinal axis of the fastener; and a wedge formed in the non-driving transition contour of the wings to present a tapered interface surface, wherein the recess is configured to engage in a mating engagement with a corresponding driver bit end having straight drive walls parallel to the longitudinal axis during the mating engagement and a radius at a transition contour greater than a recess inner root radial distance and less than a recess top radial distance and further having a bit end diameter and defining a driver lobe engagement length with each of the driving surfaces of the fastener, wherein a ratio of the driver lobe engagement length to the bit diameter during the mating engagement is greater than 0.11, wherein the mating engagement includes a lowest frictional engagement between the tapered interface surface and a straight-walled transition contour of the driver bit end parallel to the longitudinal axis that is above a bottom of the tapered interface surface and within a lower one third of the recess, and wherein during the mating engagement the driving surfaces of the fastener extend to the lowest frictional engagement, wherein each tapered interface surface is concave, having a radius of curvature greater than a radial distance from the longitudinal axis to the tapered interface surface.
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