This pack is reasonably priced and has various sizing options. Will not be purchasing any products from them ever again. I have to adjust them periodically to make sure it keeps a tight fit and seal. Works very nicely, only complaint is even though it has 4 microphones it still doesnt help differentiate if the noise is coming from the left or right side which can be a bit disorienting. so happy! Very expensive for what it is. They are also extremely comfortable, I changed the rubber mold to the medium size mold which was better for my ears and this was also really easy to do. When I applied aveeno Cream, the eczema got worse. But maybe thats just for me. The ?UC? version just means that it comes with a little USB receiver/transmitter (BT600) that plugs into your computer.