Comparison : Item # WH-720SA9, Sprocket Number WH-720S
Item # WH-720SA10, Sprocket Number WH-720S
Item # WH-720SA11, Sprocket Number WH-720S
Item # WH-720SA19 HT, Sprocket Number WH-720S
Item # WH-720SA21 HT, Sprocket Number WH-720S