Vivaglory Adjustable LED Dog Safety Collar Light for Pet Available in 7 Colors & 4 Sizes Improves Dog Visibility & Safety: The ultra-bright led collar makes your dog visible and seen at night or in dark and the superior durable nylon maximum strengthen your beloved dogs safety Battery Included: 2 x CR2016 batteries included; The battery is replaceable Convenience & Safety: The dog collar is adjustable and with the quick-release buckle ensure perfectly fit 4 Flashing Modes Available: Solid Light, Fast flash, Slow flash and Off Sizes: 4 sizes available: S-XL; Please kindly check the measurement for getting a right size collar for your beloved dog