Review on Luminous Colored Marble Pieces for Decorative Purposes by Alexander Scharon

My 6 year old loves these but they are not the best quality. Aside from being smaller than expected, they are all different sizes too! The differences are very noticeable. A few of them are also clearly not round. But my son loves how they go through his various marbles and they add another dimension to the game, especially when we pit them against his other larger balls. Great for learning! Not great if you're looking for quality marbles to play with.