These lights are simply a strand of highly flexible wire with LEDs on them attached to a battery pack with a switch.
They offer lights in a variety of colors, but I went for the traditional blue, green, orange, etc., colored lights.
They're about 9 feet long and I found that they fit perfectly around my frame.
The lights say they're for indoor use only, but I found they survived rain, snow, and harsh Chicago wind and cold. On two AA batteries they lasted all December and are still going strong into January. These gave me a lot of illumination from the side on dark Winter evenings.
A little electric tape did the trick to secure the battery compartment to my seat post under the saddle. I also used electric tape to secure the wire around the frame. If I had a rear bag under the saddle I could have just as easily tucked the battery compartment under there.
The light mode can be toggled from off to blinking to slowly fading to staying on constantly.
I was afraid the wire could come loose while I was riding and get caught in the wheels or drive train, but thankfully the tape held fine and that was never an issue. I imagine zip ties would have worked well too.
For a cheap easy way to get some seasonal lights on your bicycle, I think this and similar products work great.