All chalk brands claim to be 100% Magnesium Carbonate. When you run the tests though, the truth is that they all have significant amounts of impurities, drying agents, heavy metals, and other fillers. We’re the first to admit that our chalk isn’t 100% pure; it would be extremely expensive and impractical to make. But our chalk has a staying power that can't be beat, meaning you can chalk up less, perform at your best, and keep your hands healthy and strong. Check out what others say when they try our chalk.