This is Graft 2, which he explains stands for "geopavement and railways accelerated testing facility".

BBC: World's railway future born in Edinburgh test lab

To ensure stability and reliability for individual drives, all drives undergo rigorous high-temperature burn-in tests and accelerated usage simulation testing.

ENGADGET: Plextor M5 Pro bulges SSD envelope with 94K IOPS and 540MB/s

Those findings have accelerated a nascent trend among amateur cycling associations to start testing the winners of their races.

WSJ: Cycling's Minor Leagues of Doping