Inside each textured cube is a ball that rattles. But it does more than that! As little ones stack the cubes onto the elephant roller and onto each other, the weight of each ball aligns them and holds them in place. No more frustration. No more tears. Just easy stacking that encourages little ones to keep exploring and keep discovering! Roll into a happy tactile-learning adventure with the Lamaze Stack Rattle & Roll Blocks. 6+ months.