What is d3o? d3o is a specially engineered material made with intelligent molecules, molecules designed to be viscous and malleable under normal conditions. This makes d3o padding very soft and comfortable against the skin. However, upon impact, these same molecules in the d3o protective padding lock together and become rigid. This ability for the d3o padding to transform itself from soft to rigid is what allows them to absorb the energy from the impact, which ultimately protects you from that very same shock.