This is a BRAND NEW aftermarket Yamaha YFZ450 rear axle.
This is +2" wider than stock, giving you better stability, especially at high speeds
It is heat treated, and stronger than the stock unit its designed to replace
It will fit any year Yamaha YFZ450 2004-2009, but the nuts are designed for the 2004/2005 style OEM #90171-14037-00
This uses all the stock components (nuts, carrier, hubs, etc) - and is a bolt on direct replacement for the OEM version.