Each package contains 1 Boston Butt.
The History behind the Boston Butt (according to Wikipedia):
"Boston butt or pork butt is the American name for a cut of pork that comes from the upper part of the shoulder from the front leg and may contain the blade bone. Boston butt is the most common cut used for pulled pork, a staple of barbecue in the southern United States.
In pre-revolutionary New England and into the American Revolutionary War, some pork cuts (not those highly valued, or "high on the hog", like loin and ham) were packed into casks or barrels (also known as "butts") for storage and shipment. The way the hog shoulder was cut in the Boston area became known in other regions as "Boston butt". In the UK it is known as "pork hand and spring", or simply "pork hand".
In Spanish the cut is known as paleta de puerco,and is the main ingredient in the Mexican dish carnitas and in the Cuban dish lechon asado.
In Mexican Spanish, this cut is known as the espaldilla (literally "little back").