18 months & up. The 1 - 10 Stackers will help children learn early number concepts and are ideal to support early number sense and counting. The stacker bases measure 2" and show four different representations for each number: numeral, standard 1-5 dice array, random dot array, and 10-frame pattern. Made from responsibly sourced beechwood, each set includes ten number posts (2.5"-7") and 55 rings.