This headband is one size fits most and the size cannot be adjusted. The headband is sewn at a 6.5" diameter (13" circumference), keep in mind that measurement is before it stretches. The bun measures approximately 1.5" across. The Waffle material is a soft nylon/polyester/spandex blend, produced to our specifications, in the USA . Each headband is hand sewn with care in the USA.