Horse's neck hair is composed of two parts: the REINS and the MANE. The REINS are the long, thin hairs that run along the horse's neck and are used to control the horse when riding. The MANE is the thicker, longer hair that runs along the horse's neck and is often groomed and styled for show purposes. Both the REINS and the MANE are important components of a horse's appearance and can be used to identify individual horses.