The resulting material exhibits a material property called "strain rate sensitivity". Under normal conditions the molecules within the material are weakly bound and can move past each with ease, making the material flexible. But the shock of sudden deformation causes the chemical bonds to strengthen and the moving molecules to lock, turning the material into a more solid, protective shield.

In laboratory testing, d3o-guards provided as much protection as most conventional protective materials, its makers claim. But Phil Green, research director at d3o Labs, says it is difficult to precisely measure the material's properties because the hardening effect only last as long as the impact itself.