Purchased (4) of these for our talent show. We had to replace older Head sets that would not work (interference) because of the 600Mz change and newer wi-fi installations. These Shure headsets work great and everybody is now very happy. Only one issue - one of the receivers will not charge the (included) rechargeable battery for the battery pack. I have to put the battery in one of the other receivers to charge it. I will be bringing back the receiver for a replacement.