The Stonelined Trombone Straight Mute Series has been a favorite of players and directors since 1935. The Stonelined Straight Mutes feature a precise and crisp sound throughout the entire register of the instrument with excellent intonation. The Stonelined Series is perfect for use in jazz symphony concert band and studio work. The Humes and Berg mutes are considered to be the industry standard and are often copied but rarely equaled. These guys know all the physics behind how mutes work and have been developing products for years. They are also economical compared to some of the custom mutes on the market today