These are great to throw into your bag, and you'll ride home safely in the event that you forgot your regular lights or left them at home on purpose.
The red light is also nice in the car if your passenger wants a little light at night to look for something.
I spent $40 on a pair of lights from REI. These lights blow those out of the water. Bright, light and stay in place on your bike, these are quality items for cheap.