DDC Racing Yamaha rear sprockets are the longest lasting, toughest sprockets in the known universe. They are built from a secret proportional blend of Unobtanium and Adamantium, which we call Chromoly here on Earth. Each DDC rear sprocket is guaranteed for 1 year, so if you are hardcore enough to wear it out then we will replace it no questions asked... (well, maybe we will ask if we can ride with you?) They are designed to withstand anything you can possibly encounter while riding your dirt bike; rocks, sand, mud, stumps, bottomless river crossings, vicious rodents with big teeth, ....seriously! -Anything!