This is a NEW complete Yamaha YFZ 450 fuel petcock knob + screw for the gas tank.
This item is brand new, directly from YAMAHA, and an original OEM factory piece.
It has never been used, and will fit any year 2004-2009 YFZ450, also the 2012 and 2013 (not EFI)
It’s the selector knob that you can set to ON, OFF, or RESERVE.