The daddario bowmaster bow grip is an innovative aid for players who are developing their bow holds. Becoming comfortable with the bow is one of the most important techniques to master on string instruments but it also is one of the most difficult. The bowmaster aims to help with bow hold and is easily attached to many different types of bows. The grips low profile enables you to store your bow with the grip on in most standard bow cases or instrument cases. To attach simply unscrew the frog from your bow and slide the bowgrip on then reattach the frog and youre good to go. There are two sizes available depending on the size of bow that you use. The medium bow grip is designed for 1 2 and 1 4 size violin viola and cello bows. The large size is designed for 3 4 and full size violin viola and cello bows.