New Gates DriveAlign idler pulley.  Pulley includes bearing, and mounts on A/C tensioner.  This pulley will only work with FACTORY tensioners.  If your tensioner has been replaced with an aftermarket one, this pulley will not fit.  Fits the following:

97-10 LS1/LS6/LS2/LS3/LS7 Corvette
98-02 LS1 Camaro
98-02 LS1 Firebird/Trans Am
04-06 LS1/LS2 GTO