Most expensive Augmented Reality (AR) headset

The most expensive augmented-reality headset is the Gen III Head-Mounted Display System (HMDS), designed for use by pilots of the F-35 Lightning II Joint Strike Fighter and revealed to the public in March 2016. This 2.17-kg (4-lb 12.8-oz) carbon-fibre helmet contains a miniaturized computer that interfaces with the fighter's systems, projecting important information as an augmented-reality overlay on the inside of the pilot's visor. All this tech comes with a hefty price tag, however: the helmet, which was developed as a joint venture between military contractors Rockwell Collins (USA) and Elbit Systems (Israel), costs $400,000 per unit.

In addition to displaying flight instrument data (such as airspeed, heading, altitude and so on) the helmet's AR overlay also highlights enemy and friendly aircraft, even if they're beyond visual range, and can tag targets on the ground.

Most impressively, the system projects video feeds from an array of cameras (with both regular and night-vision modes) on the exterior of the aircraft. This allows the pilot to look straight through the floor of the cockpit, for example, to see targets on the ground below. The lining of each helmet is custom-made, based on a 3D scan of each pilot's head.