Hytail Ponytail Hat, Women's, Black S/M Small/medium fits most women. For best fit, take head circumference measurement. Small/medium fits up to 55" circumference. Designed for a sleek look, comfort, ease-of-wearing and protection from the sun. Shaped to easily fit your head comfortably. Wide band on the back lifts your hair off of your neck to help keep you cool and comfortable. Also great for wearing large, stylish sunglasses with no hassles.