Features: Bass diaphragm, oval track type, fancy high elastic rubber edge, to ensure good elasticity and tension. Exquisite workmanship and very special rubber edges, DIY wireless speakers are a very good choice for enhancing low volume. In the speaker, the passive diaphragm is driven by the active speaker unit to passively sound the air in the cabinet, and it has a better performance. 120mm x 60mm vibration plate speaker auxiliary membrane audio woofer vibration diaphragm . Used for woofer / subwoofer auxiliary membrane;enhance the effect. Specifications: Material:Rubber+Iron Color:Black,Silver;(Optional) Size:Approx.50x80mm/1.97x3.15in Quantity:2Pcs Note: Please allow 1-2cm errors due to manual measurement,pls make sure that you do not mind before you order. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Package includes: 2x Bass Passive Radiators