Cloaks any allied structures and not attacking units around the center of its diameter
It generated a large "stealth bubble" that warped light and rendered all units within the bubble invisible to the naked eye or regular sensor equipment. However, its main drawback was the amount of power it needed to function properly. During the Firestorm Crisis, Nod built Mobile stealth generators which could be used to 'creep' an assault force right up to the enemy base.
The Mobile sensor array was able to scan through its cloaking field as a countermeasure. The Stealth generator also required huge amounts of power and would shut down during blackouts and ion storms.
Nod constantly developed their stealth technology and by the Third Tiberium War was able to develop an inexpensive, but effective, replacement for the stealth generator - the Disruption tower. After the conflict, Nod began making using of smaller stealth generators which they began placing within their Crawlers in the aftermath of the Tiberium Control Network Conflict in the years leading to the Incursion War.
The stealth generator was not encountered until in the final stages of the Second Tiberium War. GDI first came across the device as it assaulted the Banshee prototype facility with the assistance of the Forgotten. Once the mutants discovered the location of the facility, the whole base was cloaked to prevent GDI from learning its defensive capabilities. However GDI later learned that the generator malfunctioned during ion storms as seen in Weather The Storm. In Final Conflict Nod attempted to hide the positions of their ICBMs and Kane's Pyramid housing the World Altering Missile, but eventually without success.
In the Nod campaign the stealth generator was first made available in the mission Destroy Mammoth Mk. II Prototype. It is available in all Nod missions that involved base construction afterwards.