Black MDF wooden Math equations clock, 12 inch diameter, Easy to read Every hour marker has a unique math equation that equals to the hour number it represents COMPLETELY SILENT non-ticking red sweep second hand - NO humming sound, Silver hour and minute hands Battery operated 12888 quartz movement, keeps accurate time, PERFECT GIFT for teachers, engineers, professors, etc. Will fit in well with class rooms, family rooms, bedrooms, study room, office, or conference room