Included is everything you need to electrically isolate your networked audio: 

Two TP-Link MC200CM fiber media converters with 9v power supplies; and

Two Tripp-light fiber-optic patch cables, one 1' long and the other 16' long.

As Michael Lavorgna wrote in Stereophile:

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The idea, implementation, and improvement are all simple; use two fiber media converters between all your noisy network stuff like routers, NAS, and server...and your audio stuff. This way, all that electrical noise from the noisy stuff cannot get into your audio stuff because they are separated by a length of fiber optic cable which does not transmit electrical noise.

Lavornga's article, with step-by-step instructions, is here:

https://www.audiostream.com/content/electrically-isolate-your-networked-audio

I did this, and it really improved the quality of the audio on my streaming device (a customized PC in my case). I've subsequently switched to a different system and no longer need these. Here's what Lavorgna said about the result:

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Electrical noise sources are like opinions, everybody has one (OK, more than one). How many will depend on your setup and how much noise they introduce into your networked audio depends on damn near everything that's connected to your network and even things aren't. All this to say, your mileage may—OK it most likely will—vary when dealing with noise.

 

In my network and in my hi-fi, adding the TP-Link Media Converters and Fiber in between my router and switch improved the sound of my hi-fi. These improvements included an immediately recognizable lower noise floor as evidenced by an increase in perceived loudness, greater clarity across the board, and a larger and more focused sound image. In other words, all good.

 

I could go on talking about specific bits of specific recordings and how they changed but that's all really beside the point since these changes are not recording-specific: They are changes in the presentation of networked my hi-fi system.

 

Current cost of these new on Amazon:

18.13 Tripp-Lite 16' fiber-optic patch cable
16.62 Tripp-Lite 1' fiber-optic patch cable
55.98 2 ea TP-Link MC200CM fiber-optic media converters @ 27.99 ea
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90.73 total cost new

I'll ship it all to you bubble-wrapped in a USPS Medium Flat Rate box, and you can be up and running in a few minutes.