Our Groove set of 4 hair + wristbands is amazingly bold and bright with retro colors and patterns to get you feeling groovy as a bracelet and while holding your hair up in style. 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" Please allow 5-8 business days for shipping.