This analog display wall clock is made of high quality acrylic material with white letters and numbers, perfect for classroom or office.As the clock is ticking, the hands move around the dial, showing the time of day through a different math problem for each hour. It's a unique and way to keep track of time. This wall clock is a and challenging exercise.The black dial looks like a chalk board. Each math equation is painted to white chalk. of using Roman numerals or numerals, this wall clock has a different equation on each delimitation.It has to be a very fashionable decoration for the wall, especially for the classroom, office and study, and an perfect gift for your or their children.It can exercise and will help you maintain vitality when you see the clock . It's also the perfect office clock for an , mathematician, or anyone who works with numbers.Name: Wall ClockMaterial: acrylicColor: Black supply: 1 x AA battery (not included).Diameter: approx. 30 cm.Package Contents:1pcs x wall clockOnly the above package content, other products are not included.Note: Light and different displays may the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.