Offspring of a male ass and a female horse .
The less common cross of a female ass and a male horse is called a hinny. Most mules are sterile. The mule resembles the horse in height and in shape of neck and croup (rump); it resembles the ass in its long ears, small hooves, and short mane. The coat is usually brown or bay. Mules are 12–17.5 hands (50–70 in., 120–180 cm) high and weigh 600–1,500 lbs (275–700 kg). They have been used as pack animals for at least 3,000 years because of their ability to withstand hardships.