One size fits all. Works on all hair types. It is used by women and girls of all ages. 1 piece. It is adjustable. Tip: Please adjust carefully so that you do not break the product. e-pony is made out of flexible and fragile plastic material. WARNING: this product is made out of flexible plastic and the teeth can be fragile. Please handle with care and use gently and carefully. We are always improving the material so that it doesn't break easily. It can be left open at the top to get that Kim Kardashian, Hollywood, runway look in the convenience of your own home. Mia e-Pony is an "e"longated ponytailer also known as a modernized banana clip, hair styling tool.