Pro Staffs were originally manufactured at Wilson's River Grove plant near Chicago. In an effort to cut down on production costs and, reportedly, improve quality control, Wilson moved production to a new facility on St.
Vincent Island in the West Indies. Rackets made at this facility have been assigned mystical qualities by many players mainly because rackets produced there were the only rackets that Pete Sampras would use throughout his entire professional career. In the early 90s, Wilson again moved production; this time to Taiwan and China, again undoubtedly to cut costs. The later Asian versions are also of high quality. However, purists are not convinced that they measure up to the standard set by the "legendary" Saint Vincent rackets.
Below is a table showing, to the best of my knowledge, the different versions of the Pro Staff Midsize rackets and their distinguishing characteristics (also see legend below the table). Order: order in which model was manufactured with respect to time. Name: PRO STAFF or PRO STAFF 6.0. Code location: at bottom or on top of "W" on buttcap. MIDSIZE: written on outer edges of throat: x2 = writte on both sides; x1 = appears only on one side; 85 = MIDSIZE 85.
Origin: SV = Saint Vincent Island, West Indies. NOTE - in the blank row there sould be mention that some pro staffs were briefly produce in Belgium by Donnay with buttcap code xxB. The item "Wilson Pro Staff Midsize 85 St. Vincent BYQ 4 1/2 9/10 condition SAMPRAS 6.0" is in sale since Monday, June 25, 2018. This item is in the category "Sporting Goods\Tennis & Racquet Sports\Tennis\Racquets". The seller is "quaxrax" and is located in Fayetteville, North Carolina.This item can be shipped to United States, Canada, United Kingdom, Denmark, Romania, Slovakia, Bulgaria, Czech republic, Finland, Hungary, Latvia, Lithuania, Malta, Estonia, Australia, Greece, Portugal, Cyprus, Slovenia, Japan, China, Sweden, South Korea, Indonesia, Taiwan, Thailand, Belgium, France, Hong Kong, Ireland, Netherlands, Poland, Spain, Italy, Germany, Austria, Israel, Mexico, New Zealand, Philippines, Singapore, Switzerland, Norway, Saudi arabia, Ukraine, United arab emirates, Qatar, Kuwait, Bahrain, Croatia, Malaysia, Chile, Colombia, Costa rica, Panama, Trinidad and tobago, Guatemala, Honduras, Jamaica.