For 21 inch woofer, everyone has different special concerns about it, and what we do is to maximize the product requirements of each customer, so the quality of our 21 inch woofer has been well received by many customers and enjoyed a good reputation in many countries. HONGCHANG(CHANGZHOU) ELECTRONIC CO.,LTD 21 inch woofer have characteristic design & practical performance & competitive price, for more information on the 21 inch woofer, please feel free to contact us.