A fastener comprising: a first end; an oppositely disposed second end; and an elongate portion intermediate the first end and the second end and defining a longitudinal axis of the fastener, wherein the elongate portion comprises: a generally cylindrical first region adjacent to the first end, extending a distance along the elongate portion, and having a first diameter (Φ 1); a generally cylindrical second region adjacent to the second end, extending a distance along the elongate portion, and having a second diameter (Φ 2) different from the first diameter (Φ 1), wherein the second Z diameter (Φ 2) is less than the first diameter (Φ 1); and a transition zone extending a distance along the elongate portion and connecting the first region and the second region, the transition zone comprising: a radiused region comprising a shoulder defining a radius of curvature in a range of 0.005 mm to 0.5 mm (0.0002 inch to 0.02 inch); and a taper region intermediate the first region and the radiused region and comprising an angled surface defining an angle in a range of 2 degrees to 10 degrees relative to the longitudinal axis preferably defining an angle in a range of 2 degrees to 7 degrees relative to the longitudinal axis. a first end; an oppositely disposed second end; and an elongate portion intermediate the first end and the second end and defining a longitudinal axis of the fastener, wherein the elongate portion comprises: a generally cylindrical first region adjacent to the first end, extending a distance along the elongate portion, and having a first diameter (Φ 1); a generally cylindrical second region adjacent to the second end, extending a distance along the elongate portion, and having a second diameter (Φ 2) different from the first diameter (Φ 1), wherein the second Z diameter (Φ 2) is less than the first diameter (Φ 1); and a transition zone extending a distance along the elongate portion and connecting the first region and the second region, the transition zone comprising: a radiused region comprising a shoulder defining a radius of curvature in a range of 0.005 mm to 0.5 mm (0.0002 inch to 0.02 inch); and a taper region intermediate the first region and the radiused region and comprising an angled surface defining an angle in a range of 2 degrees to 10 degrees relative to the longitudinal axis preferably defining an angle in a range of 2 degrees to 7 degrees relative to the longitudinal axis. a generally cylindrical first region adjacent to the first end, extending a distance along the elongate portion, and having a first diameter (Φ 1); a generally cylindrical second region adjacent to the second end, extending a distance along the elongate portion, and having a second diameter (Φ 2) different from the first diameter (Φ 1), wherein the second Z diameter (Φ 2) is less than the first diameter (Φ 1); and a transition zone extending a distance along the elongate portion and connecting the first region and the second region, the transition zone comprising: a radiused region comprising a shoulder defining a radius of curvature in a range of 0.005 mm to 0.5 mm (0.0002 inch to 0.02 inch); and a taper region intermediate the first region and the radiused region and comprising an angled surface defining an angle in a range of 2 degrees to 10 degrees relative to the longitudinal axis preferably defining an angle in a range of 2 degrees to 7 degrees relative to the longitudinal axis. a radiused region comprising a shoulder defining a radius of curvature in a range of 0.005 mm to 0.5 mm (0.0002 inch to 0.02 inch); and a taper region intermediate the first region and the radiused region and comprising an angled surface defining an angle in a range of 2 degrees to 10 degrees relative to the longitudinal axis preferably defining an angle in a range of 2 degrees to 7 degrees relative to the longitudinal axis.