3 years & up. Children can engage in sensory play experiences with raised and indented tactile shapes and patterns. The Sensory Stones feature four raised/bumpy designs (circles, dots, wavy lines, and a grid) and four indented/hollow designs (circles, lines, zigzags, and a spiral). Refer to the included activity guide for sensory play, messy play, and mark making ideas. Each stone measures 3". Included: 8 Sensory Stones.