An impact absorbing, modular helmet that prevents or reduces injury to the user and other parties in a collision is described. The helmet has layers on the outer side of the hard casing that increase the time of impact and thereby reduces the intensity of the impact forces to reduce their injury potential. The layers may be made up of uniformly consistent impact absorbing polymer material, a polymer layer filled with air or a polymer honeycombed structure. These impact-absorbing layers may also be made and used as an independent, detachable, external protective cover that may be attached universally over hard casing helmets.