The cranial unit housed the positronic brain of an android, and the brain was protected by multiple levels of shielding that made it virtually invulnerable to most kinds of radiation as well as a high-intensity charge of electricity or a heavy impact blow. The neural network, part of the positronic brain, was also housed in the cranial unit. Both the brain and the neural nets were completely self-contained within an android's head so that the head was able to be removed and the android could maintain all intellectual functions. The cranial unit was detached from the body by depressing a small actuator located directly behind the right ear.