Four Brothers GRAVITRAX 12 Replacement Chromium Steel Balls Pack of 20

Lost your marbles? Four Brothers offers round, high quality and durable replacement chromium steel balls designed for the innovative and fun STEM marble run toy GRAVITRAX, requiring 1/2 inch balls. While these balls are designed to replace the popular GRAVITRAX toy, they will also support other games that require a 1/2 inch steel ball. Chromium steel is designed with maximum engineering properties that allow for sleek and lustrous appearance in a gray metal. Never search again, as these replacement balls are known for their incredible resistance to corrosion and hardness resulting in a long-lasting product.