The DWSM770S. The DWSM770S Bass Drum-Mounted Short 9" Cymbal Arm is the Updated Version of the Classic Bass Drum-Mounted Cymbal Arm and Comes Complete with TB12 Tom Bracket and All Needed Mounting Hardware. Cymbal Arm Includes Series Features Features Such as Toothless Tilter, Techlock and Adjustable Cymbal Seat.