A medical device comprises a catheter having a catheter shaft and a medical balloon positioned thereon, as well as a rotatable assembly disposed about the balloon. The balloon has a pre-expansion state and an expanded state. The rotatable assembly comprises a sheath, wherein the sheath is disposed about the balloon in both the pre-expansion state and in the expanded state. The sheath is rotatable about the balloon in the pre-expansion state. The sheath comprises an inner layer and an outer layer, the inner layer is in rotatable contact with the balloon and the outer layer is disposed about the inner layer. The inner layer is at least partially constructed of at least one material having a durometer value greater than that of the outer layer.