3 years & up. The Tactile Counting Stones display number arrays from 1 to 10. These stones are a great resource to introduce and support math concepts including counting, number recognition, subitizing, and number bonds. Ideal for sensory math investigations. Made from a unique stone mix and durable for use in sand, water, and outside. Stones measure 3". Included: 20 Tactile Counting Stones, with two stones of each number 1 to 10.