I am not exactly sure on the mileage, as I got this on a used bike and the owner stated 500 miles. I had about 300 miles on it and would have kept it, but the LBS told me I should switch it since I was getting a new chain. I guess to match the teeth and chain wear? It is used as you see in the picture. CS-7700 9 speed Dura Ace 12-25. $40.00 shipped in the US by pay pal.[/img]