This is a set of chains for a track bike. Some have only been used once or twice, while others have been used quite a bit for practice, so they vary. I think they are in good condition, but please understand that they are sold as-is, with no returns. The second picture shows the difference in length when the chains are lined up on the right side. I believe the majority of the chains are for 51-14, 15, and 13 tooth cogs. Thank you. Keirin, NJS, fixed gear, track bike, road bike