Via Business Insider:
The material, a structured polymer composite made of alternating rubbery and glassy layers, can absorb the kinetic energy from high impact assaults with startling efficiency. During tests, researchers blasted it with tiny glass beads that simulated the impact from a 9-millimeter bullet.
Paper-Thin Material Can Stop Bullets In Their Tracks – Business Insider
Too bad the name Under Armour is already taken.