Just a shout out to Primary Drive Steel Sprockets. BUY them! They are great! I was just going through my order history on RMATV and Motosport. The Sprockets I have on my YZ 250 right now I ordered back on "Order Date: 4/27/12" About a year old! And the teeth are slightly leaning forward, but I bet I could get another half season at least! And I have been racing mostly 2, a couple times I did 3 A classes! My 06 RM 250, Last 2 times I ordered Sprockets for it were "Order Date: 4/15/08" and "Order Date: 3/22/10" That's right, Almost 2 whole years! I raced 2 B classes in 09 till I marked into A July of 09, only one class in B's in 08 though, 2 A classes in 2010. I always buy Primary Drive steel sprockets, and will continue to buy them! Because they last! Not saying other companies steel sprockets don't last, but for $29 for both front and back sprockets! That's money well spent!