Our GROW set includes five hair tie bracelets in colors representing a growing seed: soil, sun, water, sky, and leaves. The sturdy palm trees on the charm reminds us to start small and grow tall. Medium is the size of a normal hair tie band. It fits wrists between 5-6.4" around. Small is better for younger girls and small teens.  It fits wrists under 5" around. Large is sized for wrists 6.5-7.5"