Each tube has a mirror on the side, and as you've probably gathered, you can click the top to make it light up - perfect for touch-ups in dark bars, lounges, cars, etc. The actual product is pretty excellent as well - light, glossy and/or shimmery (about half of the colors have a bit of ultra-fine glitter), with a subtle flavor that matches the shade - chocolate goes with sheer brownish rose, peach with a shimmery coral, and so on. Ideal for a night out and girls like me who need a mirror and good light to apply their lip gloss (for some reason I can handle mascara with no reflective surface to guide me, but lipstick or gloss? It'll definitely end up on my teeth or face. Odd, I know).
Buy it online at Drugstore.com or Ulta.