I bought the Shure SM31FH headset wireless mic to replace another Shure mic headset that was not functioning properly. The informtion given about the product said it would fit any Shure wireless system - and I am delighted that it does indeed fit my existing Shure wireless system. I ordered it on Monday morning hoping it would arrive by Friday and it actually arrived a day earlier, so excellent service from Thomann. The mic has good sound but is picking up some breathing sounds at the moment. The advice is to put the mic at the corner of the mouth, but I am not very big and the headset cannot be adjusted to fit my small head. Thus the mic sticks out a bit. I do prefer to have an adjustable headset, but, having said all that, I am still very pleased with the microphone so far, after 1 week's use. The price was reasonable too and much cheaper than having to buy a complete new system.