The Depusheng Rev3900 Is A Professional Ktv Pre-Effector With Multiple Effects, Product Features Built-in microphone receiver, no need to connect wires, simple operation, line-of-sight receiving 30 meters KTV pre-stage reverberation effector: New upgrade, built-in effect chip, Bluetooth connection to enjoy music. Multifunctional input port: front panel 2-way/rear panel 2-way microphone input interface, which supports microphone volume adjustment/bass adjustment/treble adjustment; Optical fiber/Bluetooth/USB audio input is supported. Intelligent one-button howling prevention: Using multi-point frequency shift technology can effectively suppress howling, and at the same time avoid voice collapse, so that your singing is incisive and vivid. Various music parameters fine-tuning: Using hidden metal adjustment knob, you can adjust music and vocals in detail, and you only need a single screw to adjust, so you can easily obtain professional singing level. Widely used: weddings, concerts, bars, outdoor performances and other occasions.?If there's any problem, please don't hesitate to contact us, we are very happy to help and strive for good customer service.? Shipping: Shipping is complimentary within the lower 48 US States. We Do Not Ship to PO/APO Boxes, HI or Alaska We Do Not Ship Outside of the Continental US All items ship within 24-72 hours of Payment For large items that require Freight shipping a valid phone number is required to call and schedule your delivery Terms of Sale and Feedback: Feedback is extremely important to us and If you are satisfied with our transaction, please take a moment to leave Positive Feedback. YOUR Satisfaction is our #1 Priority! If there are any issues, PLEASE contact us BEFORE leaving a neutral or negative rating so that we may resolve any concerns. We PROMISE we can make you happy if you give us a fair chance. Returns / Concerns: All items qualify for returns within 14 - 30 days of receipt. Buyer is responsible for return shipping on any item that is not damaged Please be sure this is an item you want before making your purchase. Customer Satisfaction is our TOP priority! All items are IN STOCK at time of listing. Inventory changes constantly and it is impossible to maintain a perfectly accurate count of all items. Please do not penalize us if we have to issue you a refund! Thank You For Your Business!