The rings in this toy have been designed to recreate the energy quality of BG3, found in the numbers 16, 28, and 34, through the proportion of the diameter of the cut-out hole to the circular disc. Stacking rings are recommended for babies starting from 6 months of age. These toys are made of solid wood and finished with a 100% natural, unscented, food-grade, toy-safe wood butter product from Switzerland.