It's free [1][2][3].carl9170 is the 802.11 draft-n USB driver with GPLv2 firmware for Atheros USB AR9170 devices.
[1] http://linuxwireless.org/en/users/Drivers/carl9170 [2] http://wiki.debian.org/carl9170[3] https://www.thinkpenguin.com/gnu-linux/penguin-80211n-usb-wireless-network-adapter-0
