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/Blue (as shown)Material: ABS+Rubber Size: Outer Diameter 17cm/6.7", Inner Diameter 10.6cm/4.17", Height 10cm/3.93" Ring Glue Size: Inner Diameter 13.5cm, Outer Diameter 18.5cm Weight: 190g / 6.7oz Using Method: First Put in the Protective Sticker on the Skin Drum Kick, and slice lengthwise on the inner diameter of the circle to make a full 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 StickerNote:Please refer to the measurement. A small measurement error is acceptable within the normal range. There may be a slight color difference due to monitor, camera or other factors, please refer to the physical item.