Shield of Sand

Whenever Gaara is about to come to harm, a shield of sand will automatically surround and protect him. The sand will react regardless of Gaara's will, even protecting him from self-inflicted injuries. This was first believed to be enacted by the One-Tailed Shukaku's desire to survive, although it was later revealed that Gaara's mother, Karura, had her love and will seeped into it.

The shield is capable of withstanding considerably strong attacks and projectiles, and can be hardened to a point where it's stronger than even Raikage's strength and the Gold Dust. The shield is so fast that even Sasuke's Amaterasu failed to breach it, earning the name.

In Part I, the shield's power was considerable in speed and strength. However, it could have been easily defeated with extreme speeds and brute force, such as Sasuke's Chidori and Rock Lee's Reverse Lotus. In Part II, however, the shield showed a great increase in speed, to the point where it could guard against Amaterasu and defend against the Fourth Kazekage's Gold Dust.

Gaara can also completely surround himself in the shield to further increase his defensive capabilities. He then uses the Third Eye to watch his opponents' movements and control sand as necessary to battle them. In addition to being extremely dense, this sand-sphere can form spikes from its surface to spear any would-be attacker. He can also use this technique in mid-air as he did while fighting Deidara. Gaara can use this technique to shield himself from his opponent long enough to perform his transformation into the One-Tailed Shukaku. With sufficient force, such as the Chidori or an explosion, this defence can be breached through.

Trivia

 * Despite that Shukaku was stated to be the source of this technique, it has remained with Gaara even after the beast was extracted from his body. Both Gaara's father and uncle have stated that it is his mother's will that moves the sand to protect him and not Shukaku.