Dimmer Switch For A NeoPixel Ring
Neopixels are not like normal LEDs, they require some sort of a computer to send the data to tell them what color and brightness to display.

Typically people do this with a small and cheap computer like an Arduino. 

You can also control the NeoPixels using a normal computer and a board like the FadeCandy...

https://www.adafruit.com/product/1689

The FadeCandy connects to the computer over USB and then you run  a program on the computer to tell the NeoPixels what color to display. 

I have not seen a commercially available, stand alone NeoPixel controller- although it would not be hard to make one. 

If you want to control your NeoPixel ring, I think you are going to have to dig in make your own controller! 

Here is a very cheap and popular tiny-computer (called the Teensy) that is very popular for driving NeoPixels...

https://www.amazon.com/SparkFun-Teensy-3-1/dp/B00NC42Y64/ref=as_sl_pc_ss_til?tag=joshcom-20&amp;linkCode=w01&amp;linkId=WAVCBDPYGTR3YIZH&amp;creativeASIN=B00NC42Y64

...but there are plenty of others.