Review on Noctua NF A4X20 FLX Premium 40X20Mm by Eloy Boelkens

I bought 2 of these fans to replace the stock fans in the Unifi USG Pro 4 Security Gateway after finding this model recommended for this fan on several forums. The standard fans in the USG Pro 4 are loud, but have an unusually high-pitched sound. The stock fans measured over 55-58dB after only changing the dropout sound by 8dB, however the high pitched tone was removed making the sound much less noticeable. Note. I didn't use either of the two optional noise canceling adapters as I wanted to retain maximum air movement. The fans appear to be well made, well packaged and come with all the necessary mounting hardware.