Features:1. Tuned port designed for bass drum2. Extend your low-end frequencies3. Add more punches to your audio4. Make the bass part more powerful, and the effect can be adjusted; Simply adjust the integrity of the drum surface5. The revolutionary amplifier instantly improves the sound of any bass drum. Description:Colors: Black/White/Red (As Shown)Material: ABS+Rubber Inner Diameter: 10.6cm/4.17in Size: Outer Diameter 18.5cm/7.28", Inner Diameter 10.6cm/4.17", Height 10.5cm/4.13" Weight: 190g / 6.7oz Using Method: First, put the protective sticker on the drum skin and cut along the inner diameter circle to make a complete circle. The rubber part of the speaker is stuck on the skin of the drum and the installation is completePackage Included:1 x Bass Drum Amplifier1 x Protective Sticker