You wear the Remee Lucid Dreaming Mask just like a regular sleep mask, but it includes a built-in LEDs that flashes in patterns. Then in your sleep, you hopefully recognize the lights as something that normally doesn't occure, and then become aware that you are dreaming, and then have fun in the lucid dream.
It also comes with another little feature, Nap Mode where it will start to flash a short time after being activated. It makes it so you don't have to reprogram it from several hours of sleep to several minutes of sleep and back. This mode is also great for those “going back to sleep" moments on weekend mornings or days where there's no rush to get up.
It also has dimmer control so the lights don't wake you up by being so bright on your closed eyes.
You use a web site to change the settings.