Material: PVC Style:Styles As Pictures Shown Diameter 18.8cm(7.40in) Inner diameter 13.5cm(5.31in) Product Name: Bass Drum Port Hole Protector Special Design: Tuning port designed for bass drums. Great Function: Expand your low end frequencies. Rubber drum ring:The rubber drum ring is tightly fitted to the drum surface, which can be adjusted by adjusting the tightness of the drum skin. Drum Body: Made of environmentally material, durable and not easily deformed. This product converts the kick drum into a bass reverb speaker, enhances the bass audio advancement, concentrates the air in the drum cavity, and compresses it inside, making the bass part more powerful. The effect is adjustable, just adjust The drum of the drum can be tight. New And High Quality Packing:1PCs Due to the difference between different monitors,the picture may not reflect the actual color of the item Please allow 0.1-1cm(0.04-0.39in) differs due to manual measurement,thanks