Grow sparkling, colorful crystals overnight from a safe solution of potassium aluminum sulfate. Single out the largest crystal shard, redissolve the remaining crystals, and repeat the crystal formation process to grow a larger, more striking crystal. This kit includes four packets of crystal-growing salt and two dyes (red and blue) so you can grow a variety of crystals in different sizes and colors. For Ages 8 and up. WARNING: CHOKING HAZARD – Small Parts. Not for children under 3yrs.