Guidecraft IO Blocks Minis - 250 Piece Set, Miniature Building STEM Educational Toy Open-ended, friction-fit construction toy with digital world design roots: IO Blocks, now in a Mini (quarter-size) version. 250 small, colorful, soft-touch matte plastic pieces securely interlock with unique, friction-fit system. Use free build app as a creativity guide. Available on Google Play and the Apple App store. Educational focus: STEM, fine motor and problem solving skills, and spatial concepts. Suggested Age: 5+