NERA and NxRA operate similarly to explosive reactive armour, but without the explosive liner. Two metal plates sandwich an inert liner, such as rubber.[1] When struck by a shaped charge's metal jet, some of the impact energy is dissipated into the inert liner layer, and the resulting high pressure causes a localized bending or bulging of the plates in the area of the impact. As the plates bulge, the point of jet impact shifts with the plate bulging, increasing the effective thickness of the armour. This is almost the same as the second mechanism that explosive reactive armour uses, but it uses energy from the shaped charge jet rather than from explosives.
Since the inner liner is not explosive itself, the bulging is less energetic than on explosive reactive armour, and thus offers less protection than a similarly-sized ERA. However, NERA and NxRA are lighter and completely safe to handle (and safe for nearby infantry), can theoretically be placed on any part of the vehicle, and can be packaged in multiple spaced-out layers if necessary. A key advantage of this kind of reactive armour is that it cannot be defeated via tandem warhead shaped charges, which employ a small forward warhead to detonate ERA before the main warhead fires.*
*Wikipedia
What's "SLERA?"
But i think it's educational. In part 3 of Anatomy of an Abrams Tank the narrator said that the turret is protected by a combination of glass and ceramic materials.
