The Addasound SR2821 was discontinued 2 or 3 years ago but the construction looked decent from our point of view. It was replaced with the Addasound Crystal SR2831 which features a larger high fidelity speaker but we are not certain about the construction. All we can tell you is that we have been selling these for about 2 years and had no returns. Like your SR2821,  all Addasound microphones include a 2 year manufacturer warranty.

We have tested but not heavily used the Philips SpeechOne. When it comes to construction, it is very rugged; as in the king of the hill. You can tell when you put it on because it is about 4 times heavier than other headsets. Our favorite SpeechOne comfort feature is that you can set the headset up so that only 2 small memory foam pads touch your head. This also keeps it off your ear. The accuracy is nearly as stunning as the high price, which appears to be it's only negative.

We haave heard of a few examples of an MB Pro 1 UC/ML interfering with the Bluetooth keyboard  but accuracy should have been eexcellent.

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