Bass Drum Bottom Microphone Speaker Voice Sound Amplifier Drum Accessories Bass Hole Protection Drum Spare PartsFeature:1. Made of environmentally friendly ABS material, which is durable and not easy to deform.2. Bass drum design tuning port to extend low-end frequency.3. The drum ring fits tightly on the drum surface, which can be adjusted by adjusting the tightness of the drum skin.4. The bass reverb speaker can improve the bass sound drive, concentrate and compress the air in the drum cavity to the center, making the bass part stronger. The effect is adjustable. Simply adjust the tightness of the drum.5. The inner diameter of the drum should be cut along the wheel to avoid unnecessary damage. Specification:Material: ABS Hole: Red, Blue Speaker Size: Inner Hole Diameter: 10.6cm/4.17in, Outer Hole Diameter: 18cm/7.09in, Height: 10cm/3.94in Ring Glue Size: Inner Diameter: 13.5cm/5.31in, Outer Diameter: 18.5cm/7.28in Usage:First, attach the protective sticker to the hole to the bottom skin of the drum, and then draw along the circle of the inner diameter. When the full circle is drawn, the rubber part of the speaker is locked and the drum skin is installed. Note:Due to the different monitor and light effect, the actual color of the item may be slightly different from the color showed on the pictures. Please allow 1-2cm measurement deviation with