Eccentric design allows the head angle to be changed by 1 to 1.5 degrees and bottom bracket height to lower or raise by shortening or lengthening the effective eye to eye of the shock. Slacken the head angle for steeper courses or steepen it for sprinting. 6mm hardware provides the greatest amount of alteration. Used on World Cup circuit by many of the top riders. Made from Grade 5 titanium, which is significantly lighter than steel hardware . Sets of 2 for 1/2″ shock eyelet shocks, see www.burgtec.co.uk/ for frame fitment chart