Wilson has since produced numerous Pro Staff models, including some based closely on the design of the Original. The "descendants" of the Pro Staff 6.0 usually bear the moniker 6.1 in the frame title and have incorporated larger head sizes (90–95 sq in) and more modern graphite composites in their manufacturing, including the production of curved beam rackets instead of the traditional box beam design used in the original Pro Staffs. Most professionals using these rackets choose the head size, with the notable exception of Roger Federer. In recent years, Wilson has phased out the box beam for a more modern curved beam on most of the 6.1 rackets with the exception of the Tour/90 model, which retained the box beam design. However, in 2012 Wilson rereleased the box beam design by separating the 6.1 rackets into two categories, 6.1 ProStaff (which retained the box beam design), and 6.1 (which kept the curved beam design). They further clarified the division in 2014, removing the "6.1" label and releasing the ProStaff as a stand-alone racket series.