The American Staffordshire Terrier (Amstaff for short) is a bulky chunk of muscle with the strong jaws typical of a “bull breed.”
Amstaffs are generally friendly dogs, but they do have strong protective instincts that can be enhanced through training.
Temperament: The American Staffordshire Terrier should give the impression of great strength for his size, a well put-together dog, muscular, but agile and graceful, keenly alive to his surroundings. He should be stocky, not long-legged or racy in outline. Height and weight should be in proportion. A height of about 18 to 19 inches (46 to 48 cm) at shoulders for the male and 17 to 18 inches (43 to 46 cm) for the female is to be considered preferable. – Wikipedia