Dairy Cow Twin Bell Alarm Clock with Nightlight for Kids 3" Metal case, glass lens. Size: 4" x 2" x 5", Diameter: 3" Bell alarm sound, Super loud alarm sound for heavy sleepers. Electronically controlled, no mechanical ticking to ensure a good sleeping. Powered by 1 AA battery, ordinary Carbon Zinc battery( not included). Nightlight function(built-in lamp), Simply press the button to get the light on.