external USB wireless card

[K0r33b]

Muy buenas gente, estoy siguiento un curso sobre el tema que tratamos aqui, el entorno que trabajaremos sera en una VM con Kali, y me dice que necesito una  external USB wireless card, que no entiendo para que la verdad, trabajo desde un portatil, el cual ya tiene su wifi integrado, alguien me explica para que necesito la tarjeta externa inalambrica?
Exactamente pone esto:
 Working with what you already have is fine for the course, however not
for real world pen testing
 Most things will work, and by the way some things just DO NOT.
 Does internal wireless meet the chip requirements? STOP Warning: A VM
will show up in Kali as an Ethernet adapter eth0. You can't do the wireless
lectures without an external USB wireless card when using a Virtual
Machine.
 To be redundant I did not say use the internal wireless card in a Virtual
Machine.
 To be able to do the wireless lectures in a VM, do a search for USB
wireless adapters for Kali Linux. Here are a couple of sites that talk about
what to use:
http://www.blackmoreops.com/2014/01/08/recommended-usbwireless-cards-kali-linux/
and http://www.aircrackng.org/doku.php?id=compatibility_drivers
and
http://www.wirelesshack.org/top-kali-linux-compatible-usb-adaptersdongles-2015.html