Safe to use: the shell of this brain teasers game is made of non-toxic plastic, without burrs, smooth to touch, and the tiny steel balls are confined in a transparent protective cover for safe playing; Each size is approx,10 cm/ 4 inches in diameter, proper size and light weight.Full of challenge: brain maze puzzle is a novel type of puzzle game, which is more difficult to pass, which is a funny tool for training your brain and the ability to problem solve, ideal for people who like mental activities, an ideal gift for your friends and family; The spherical shape does not need to be set-up or installed the battery, just flip the ball to the finish line.Intelligence development toys: magic maze puzzle cube is cute and interesting, you need to observe the passage and think to send the tiny ball to the end; Easy to use but hard to master, really a challenging educational toy that can cultivate your spatial cognitive ability, release stress from work and daily life.NOTE: pink: easy difficulty orange: medium difficulty blue:hard difficulty green:highest difficulty