Yamaha SB-6X-2, Silent Brass System for Flugelhorn, Latest generation with STX-2, Consists of a smaller, lighter mute with almost natural blowing resistance and the Personal Studio, which features Yamaha's exclusive Brass Resonance Modelling Technology, Dimensions of mute: 129 x 143 mm (5-1/16"" x 5-5/8""), Weight of mute: 130 g (4.6 oz.), Dimensions of STX-2: 70 x 20 x 98 mm, Weight of STX-2 without batteries: 69 g (2.4oz), Battery operation: 2x AA (not included), Includes headphones