OOTDTY New and high quality Features: Used to replace the inverted tube. Made of high-quality material, durable and stable for use. A passive radiator is used to adjust the speaker system; the designer can adjust the overall tone of the speaker. The radiators are effective in enhancing bass response, providing a booster effect with convenient tuning. Each speaker has a diaphragm unit at the back, which increases the low-frequency performance, resulting in improved sound quality. Attention: This is a passive radiator, not a speaker. It does not include a voice coil or magnet. Passive Radiator only; other accessories shown in the picture are not included. Specifications: Item Type: Passive Radiator Material: Plastic + Metal Size: (Optional) 4 inch: Horn diameter: 116mm (4.5in), Diagonal hole spacing: 108mm (4.2in), Opening hole: 95mm (3.7in), Counterbore depth + height: 2.5mm + 33mm (0.09in + 1.2in) 5 inch: Horn diameter: 147mm (5.7in), Diagonal hole spacing: 139mm (5.4in), Opening hole: 118mm (4.6in), Counterbore depth + height: 3.8mm + 37mm (0.14in + 1.4in) 6.5 inch: Horn diameter: 178mm (7in), Diagonal hole spacing: 168mm (6.6in), Opening hole: 145mm (5.7in), Counterbore depth + height: 4mm + 47mm (0.15in + 1.8in) Color: Black Quantity: 2 Pieces Note: No retail packaging included. 1cm = 10mm = 0.39inch Please allow 01cm error due to manual measurement. Ensure you are comfortable with this before purchasing. Due to differences in monitor displays, the image may not reflect the actual color of the item. Thank you. Package Includes: 2 x Passive Radiators