JT Steel Sprockets are the OEM quality choice, manufactured using only the finest grade of C49 high carbon steel for the rear sprockets, and SCM420 chromoly steel alloy for the front sprockets.
Fits:

15 Teeth
Aprilia Road
1100 Tuono V4 RR 15-21
1100 Tuono V4 Factory 15-21
1100 Tuono V4 Superpole 21