4 years & up.This product is ideal in helping develop your child's Science, Technology, Engineering and Math skills. Allow children to enhance hand-eye coordination, motor skills, logic and problem-solving skills while playing. Build a fort, rocket, boat, tower, tunnel or bridge! Design your own scientific model, or create a unique contraption, the opportunities are endless! The straws fit snugly on the connectors, and are flexible so you can build arches and tubes. Very economical! 400 pieces.