This mathematically challenging puzzle from Toysmith is a best-selling STEM introductory toy that’s hours of fun and cognitively beneficial. Small enough to fit in small hands and bag pockets for travel-sized puzzle time. Puzzles feature white and red squares with black numbers and 1 plastic barrier piece. Slide the numbers into sequence by lining them up either vertically or horizontally until all 15 numbers are in order. Can help improve hand-eye coordination, critical thinking skills, logic skills and memory recall, and more. Blue and red display case holds 48 puzzles for easy showcasing and selling.