Wilson Pro staff 90L (319G) BLX Racquet Grip Size 3 Roger Federer Signature Version 2010-2013The BLX frames we launched back in 2012 were our first using a new racket material: basalt. This new material was used to reduce the amount of racket vibration felt at impact. BLX technology evolved into Amplifeel technology, which was adding the vibration reducing effect of basalt to the racket handle. A year after the BLX Pro Staffs launched, a version with the Amplifeel handle was introduced with an almost identical design