A Heward’s handy haversack was a magic backpack that offered three compartments of extradimensional storage space. The haversack looked like an ordinary backpack and always weighed 5 pounds (2.3 kilograms) regardless of its contents.
The backpack contained two side pouches that could hold up to 20 pounds (9.1 kilograms) at a maximum volume of 2 cubic feet (56.6 l) each, as well as a main compartment capable of storing up to 80 pounds (36 kilograms) at a maximum volume of 8 cubic feet (226 l). If overloaded or damaged, the haversack was destroyed, its contents lost forever.
As with many other magic storage objects such as bags of holding or portable holes, placing a Heward’s handy haversack inside the extradimensional space created by one of such items destroyed both and opened a temporary portal into the Astral Plane that pulled through it any creature within 10 ft (3 m) of it.