Yibuy Black Bass Rubber Mute for String Double Bass with Double Holes This Round Rubber Mute for bass conforms to the shape and curvature of the bridge for better contact,good muting power and balanced sound. Installs in seconds and is easy to change. Stays in place on your instrument when not in use. Conforms to the shape and curvature of the bridge. Installs in seconds and is easy to change.