Debra Audio Pro Uhf 4 Channel Wireless Microphone System With Cordless, B) Product Features Debra Audio AU400 4 channel wireless microphone system.(Two set freuqncy point: A- 501/511.5/524/538.5 B-506/517.5/531/546.5) These series products adopt UHF frequency and use the international standard common frequency which can be used in all over the world. Due to the low frequency and many reasons, traditional wireless microphone usually disturbed by many factors especially by the variety of harmonic which send off by the CD/DVD/VCD/LD and other any digital equipments. Squelch circuit usually analysis the intensity of the RF frequency channel instead of the noise and the needed signal. Using the low traditional wireless microphone in the complex environment or when the signal of the microphone is week or the microphone is closured, the squelch circuit many suddenly opened which result the receiver send out a strong burst of noise. It ideal for church, small DJ KJ stage, birthday wedding or family party, conference, classrooms, small karaoke night etc. 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!