First of all, this is sold as a unit as it is *not* designed to be used with wireless headphones. for Bluetooth hands-free kits (remember that?). This makes wearing a Bluetooth headset significantly more comfortable and easier to hear as it isolates that ear from outside noise. I had this on an old BT headset but unfortunately it was out of place. I was happy to see that they still sell them. However, $5 per unit is still very reasonable. Look at the prices of the foam trays in question and you will see that they are comparable.
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