It looks like a key chain, easy to use just clip it on the dog’s collar or harness, very lightweight and super bright. And there are 3 available colors you can choose what you like. There is a small power switch button, push the button once is quick flashing, push twice is slow flashing, push third times the light will stay lit. If your dog has this dog night light on its collar or harness, it will allow drivers, cyclists, joggers & others to easily see your puppy from far distances, be safe at night. You can also see your dog better at the dark night.