About the D'Addario 9480 Bowmaster Bow Grip for Violin, Viola, and Cello:
 
The D’Addario Bowmaster is an innovative bow grip designed to encourage proper bow handling. Great for beginners and younger orchestral players, its innovative design helps players hold the bow correctly, making it easier to achieve good technique right out of the gate. Simply slide the Bowmaster’s comfortable rubber grip onto the bow and you’re ready to play.