Designed with a hidden screw that adjusts the tension.Perfect building toy for children learning plane geometry and solid geomotry. Best educational toy, enhance children's creativity and imagination. Made with high quality materials which is environmental-friendly, non-toxic, no harmful. Playing together, build up a positive relationship with your kids. Intelligent magnetic construction sets for brain creativity, as educational toys, these magnet toys unique shape, free combination, could develop kid’s motor development, cognitive development of color, teamwork ability, artistic cognitive, sensory, cognitive ability, imagination and creativity. Diy is always a great thing for everyone, especially for kids, they will get much happier when finished making a cute item by themselves. The magnets block toys use high quality original abs material, all rainbow color pieces have been through ultrasonic process for better tightness, perfectly prevent breaking apart. Children can transfer 2-d plane shapes to 3-d geometric structures magically ,make it safe to diy for child with smooth hand-feeling. The magnet is very strong , extremely smooth edges, no sharpness , fits for all age kids, a best way for them to explore the world of geometry and architecture. Kids can follow the idea booklet or create their own design which inspires their imagination ability and creativity and have fun ! Can be washed by water and mild soap due to its plastic materials , and the sets come with an easy-carrying plastic box which stores all the pieces. Perfect for use at home, in school and day care center.