If your Studio 49 bass xylophone or metallophone has a resonator box made entirely of wood (no plastic inner lining), then this is the cording you need to replace old, worn cording or tubing. This item is for one Studio 49 bass xylophone (contains 2 lengths of cording, one for each side of the instrument) or bass metallophone (bass metallophone only has cording on one side; the other is bare, but has the damper bar).