Pros: Bulb Durability, Battery Life, Durability, Brightness
A flashlight on every keychain!
I've used these for years, and they last and last. I have one that must be ten years old; the light is getting dim but that's pretty impressive for a sub-$10 light. My favorite use for these: we hang them on lanyards and use them in power outages (which we used to have all the time when the kids were growing up). Flick the little constant-on switch, hang it around your neck, and you've got a little pool of light right in front of your feet -- perfect for avoiding barking your shins in the dark, or stepping on the cat, or falling down the stairs. We used to get them in different colors as a way of color-coding: Mom's was orange, big sister's was red, little sister's was purple, etc. Our kids LOVED power outages. The perfect addition to your emergency kit in home or car.