Input (grade 13): The surrounding Kalahari Basin covers over extending farther into Botswana, Namibia and South Africa, and encroaching into parts of Angola, Zambia and Zimbabwe.
Output (grade 10): The surrounding Kalahari Basin covers over 2.5 million km extending farther into Botswana, Namibia and South Africa, and encroaching into parts of Angola, Zambia and Zimbabwe.