The " RIM " Blue Musical Rim Protector The protector should help maintain the finish and shape of the bell area, while also maintaining the sound quality. The protector should help reduce scuffs and dings to almost any musical instrument. Especially useful during marching season and practice. Fits Trumpets with bell size of 4.6" to 5.5" Fits Saxophones with bell size of 4.6" to 5.5"