Dogs in Play Multi-Function LED Lighted Dog Harness - Small 18" - 24" long, 3/4" wide Small harness: 18" - 24" long, 3/4" wide Correct Harness Size: The sizes listed above indicate the maximum size with the buckle fastened. Measure your pet's midsection before ordering. You may wish to add 1" - 2" to the measurement for your dog's comfort. Three different light settings allow you to choose based on your activity - Steady On (non-flashing), Slow Flashing, Quick Flashing. Runs on 4 CR2025 batteries Each side of the harness can be turned on or off separately