Wilson Pro Staff braided graphite & kevlar composite racquet with open throat and enlarged head. PWS - Perimeter Weighting System. Used by Pete Sampras in the Wimbledon final and autographed by him on the handle. The origins of the model ProStaff name come from 'Professional Advisory Staff' - Wilson contracted top athletes in a chosen field who in turn gave Wilson the right to use their name on equipment, marketed these sporting goods and developed equipment by bringing their player experience to the design table.