Methods and apparatus for a fastener head having a dual zone socket area and a mating driver bit

A fastener having a head portion with a recessed socket area extending into the head portion and a shank sharing a longitudinal axis with the recessed socket area, comprising:

• a sidewall defining the recessed socket area having a top edge and a bottom edge;
• and
• a plurality of driving surfaces and removal surfaces disposed along the sidewall, wherein:
• an upper section of the sidewall tapers inwardly towards the longitudinal axis between about one degree and about three and three-fifths degrees from the top edge to a curvilinear transition line;
• and
• a lower section of the sidewall forms a vertical surface parallel to the longitudinal axis and is disposed between the curvilinear transition line and the bottom edge, wherein:
• the lower section of the sidewall is offset in the clockwise direction from the upper section of the sidewall by a rotation of between one degree and six degrees causing the curvilinear transition line to vary along a length of the plurality of driving surfaces and removal surfaces between the top edge and the bottom edge;
• and
• a driving surface of the lower section of the sidewall at the bottom edge is aligned with a driving surface of the upper section of the sidewall to form a vertical line of insertion extending from the top edge to the bottom edge.