Switches itself on when it's getting dark and it only flashes when your pet is moving (for example when running or walking)! The latest light and movement sensors make this possible. Therefore you don't need to change the battery for months. Automatic flashing safety lights only in darkness and when your pet is moving. Automatic on/off function. Visible over 350 m. Waterproof, super-bright LEDs last up 100 times longer than conventional LEDs. With address field. Incl. batteries. Immediately ready for use.