Set up to 90 minutes of reading time, after which, the light will turn off automatically. Great if your child tends to fall asleep reading. Not your typical dim book light, this sleek unit features two bright LEDs that last 100,000 hours. Clips onto a paperback or hardcover book. Runs on three AA batteries (sold separately).LED Light The bright white LED lights illuminate the page your child is reading without disturbing those around them. Provides enough light to reduce eyestrain, but focused on the book, which keeps your child focused on the book. LED lights last 100,000 hours. LEDs do not heat up like traditional incandescents, so there is no danger if your child falls asleep and the light tips onto their book or blanket.