With Its Metal Receiver And Four Handheld Lavalier Headset Microphones, The Product Details 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. Payment We accept PayPal and credit cards via PayPal. Taxes - US We collect sales tax, as required by law. Shipping We make every effort of shipping within 3 business day of payment clearing. The estimated delivery time is 2 - 5 business days from the shipping date. Policies If you do need to return your item, please contact us via email (you will receive an email when your product ships with additional details - Subject: Important information about your purchase). You will then be provided with a return shipping label and packing slip. Pack the item carefully. Include the packing slip, apply the shipping label, and return the item within 30 business days of the date you request a return, or your return will be canceled. Once we receive your order we will inspect the return. Please allow up to 5 business days of receiving the returned item for your refund.