Dual ratio sprocket for F4i 43t stock mode and 62t stunt mode. Retail price is $800 that shipping not included from Canada. Tried it out for a couple weeks, works great, just need the cash right now. Easy come easy go. Im asking $600 thats about $250 less than buying brand new. Used a little on streets and mostly in the lots. Easy install. For more info on it goto dualratiosprockets.com Also the sprocket and chain are a 530 pitch, ill include the tool used to switch modes ofcourse.