brand new and high quality Features: Bass radiator, also known as passive speaker, is used to replace the inverted tube, the subwoofer made with the radiator and the traditional back subwoofer. Working principle: It will vibrating up and down when the speaker working, it will produce airflow, this air flow driven diaphragm,to produce low frequency. Low frequency dive depth and backward , But the sense of speed is significantly faster than the back-type. Tight box advantage, Get rid of inverted pipe mouth to bring the wind noise. Used to adjust the , the designer can adjust the overall tone of the speaker. Make great effect on enhancing the , booster, convenient debugging. Increase the lower potential of the , the sound more excellent. Vibration Membrane only, other accessories demo in the picture are not included! Specification: Material: Rubber + Iron Type: Speaker Accessories Color: Black Size: One Size Diameter:70.0mm/ 2.76in Quantity: 1 Set Note: 1.No retail package. 2.Please allow 0-1cm error due to manual measurement. pls make sure you do not mind before you bid. 3.Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you! Package includes: 2 Pcs x Vibration Membranes