This air defence technique creates a giant shield of sand that is suspended in mid-air by raising a great amount of sand from the ground. By gathering the best possible mineral-rich sand, the hardness of the shield is considered to be very high. Furthermore, the sand has its defensive strength raised by flowing chakra through it. It was strong enough to protect Sunagakure from Deidara's C3.
Kūsa, when written as 空佐, is a rank in the Japan Air Self-Defence Force. It is about equivalent to the rank of colonel.