The NerveGear is a helmet with a smooth, deep blue color. At the back, it has a wire of the same color stretched out of a long pad. It also has a battery and internal memory to store data from the games, which is how Kirito stored Yui in it. 30% of the NerveGear's weight is from its internal battery. The NerveGear's high density microwave transceivers can determine what the user's face looks like. The transceivers not only block every transmission from the brain to the body, but also from the body to the brain; while using it, the player is completely insensate to the physical world. Unknown to anyone except for Kayaba prior to the opening of Sword Art Online, the NerveGear's transceivers possess enough power to fry the player's brain with a burst of microwaves, using the power from its internal battery, and SAO's operating system has been programmed to do so if the player's hit points are reduced to zero.
At the time of the Sword Art Online beta test, there were about two hundred thousand players in possession of a NerveGear. Half of them applied for the beta test.
After the events of the Death Game incident, Argus no longer produces new NerveGear units, and most users instead use RECTO's replacement for the system - the AmuSphere, which has significantly less powerful transceivers; it is thus both incapable of doing harm to a player and completely eliminating normal sensory input.
Kirito is one of the few VRMMO players who used a NerveGear even after the SAO incident, though this is likely due to time and monetary constraints in getting an AmuSphere, as he wanted to check out the possibility of Asuna being trapped in ALfheim Online. Eventually, even Kirito switched to using an AmuSphere after the ALO incident.
To use the NerveGear, the player wears the game console over the head. Then, it's recommended that the player find a comfortable position to station the body, commonly being a bed. Afterwards, the game will load by the initiation words «Link Start».
- In the Accel World series, written by the same author as Sword Art Online, volume 4, chapter 8 of the novel mentions an unnamed VR machine that is similar in background to the NerveGear. Episode 22 of the anime adaptation of the series confirms that the unnamed machine is a NerveGear.