The access keys are ter'angreal linked to the massive Choedan Kal, the two greatest sa'angreal ever created. As tapping the Choedan Kal unaided is invariably deadly because of the immense quantities of the One Power available through them, and the fact that carrying a gigantic statue is not feasible, the access keys were created both to act as buffers between the user and the sa'angreal while being portable.