Abstract: A helmet includes an optical system presenting a rearward view to the wearer as an image below the wearer's horizontal line of sight and including a plurality of optical components arranged such that the image is viewed through a viewing component positioned adjacent to the wearer's forward line of sight and below the horizontal line of sight. The remaining components are positioned such that the optical path from the rearward view to the viewing component is routed around one side of the helmet. The optical system is housed in a "knock-off" unit and is sealed to prevent condensation. The helmet may be used by motorcyclists or security guards and provides a compact arrangement having a wide field of view.