Abstract: Systems and methods of a safety helmet for protecting the human head against repetitive impacts, moderate impacts and severe impacts so as to significantly reduce the likelihood of both translational and rotational brain injury and concussions may be provided. The helmet may include an outer shell, an outer liner disposed within and coupled to the outer shell, and an inner liner disposed within and coupled in spaced opposition to the outer liner. A damper array may allow for omnidirectional movement of the inner liner relative to the outer liner and the outer shell.

Abstract: An adjustable helmet having first and second shells and a single actuator comprising at least one tooth, the single actuator being moveable between: a first locked position, wherein the at least one tooth retains the first and second shells and the first and second shells define a first hollow space; a released position, wherein the at least one tooth no longer retains the first and second shells such that one of the first and second shells is moveable relative to the other of the first and second shells; and a second locked position, wherein the at least one tooth retains the first and second shells and the first and second shells define a second hollow space, the second hollow space being different than the first hollow space.