Goki Glass Marbles 21pcs Set of 21 glass balls by Goki that you can use in many ways The balls can be used as an addition to all kinds of ball tracks As a fun element, many possibilities For the game of rolling, sliding, rattling, catching Perfect for speech therapy exercises, blowing balls in the maze with a straw You can mark the playing field with tape After placing the largest ball in the middle, you can roll the balls so that yours are as close as possible