Vertical maneuvering equipment (Before the Fall Manga)

The vertical maneuvering equipment (立体機動装置) is a set of experimental equipment developed by inventors Angel Aaltonen and Xenophon Harkimo that allows for great mobility when facing Titans in combat. The equipment enables the user to fight in a 3D space as opposed to a 2D one. The equipment itself takes the form of a body harness that encompasses much of the body below the neck.

History
During the early days of the Survey Corps, a prodigal inventor named Angel Aaltonen expressed that the soldiers were woefully under-powered when fighting against Titans outside the Walls. His assistant Corina theorized that the height difference is a big disadvantage and they could possibly try to build a device that would eliminate that. Intrigued, Angel started brainstorming ideas and incorporated the thought of using iron bamboo as the base of a bladed weapon to go with the device. During a trip to the Industrial City, he presented an early prototype of his device to both his friend Sorum in the Survey Corps and fellow inventor Xenophon Harkimo; both were impressed by it and saw the possibilities. Xenophon agreed to work with Angel to improve and streamline the device.

The first improvements occurred after the Titan Mammon invaded Shiganshina District, killing numerous citizens including Corina. Learning the nape of the Titan's neck was the weak spot ( as well as participating in two expeditions with the Survey Corps), Angel learned much and continued to work on the device. However, Angel losing his sight and going into self exile stalled production of it for some time; Xenophon took it upon himself to carry on in his friend's absence and would work on the device for the next fifteen years.

However, Xenophon would figuratively hit a wall and production began to stall once again. Eventually, two teens named Kuklo and Cardina would be sent under Xenophon's care; they were tasked with testing the device and took notes on their observations; this would help work out some of the flaws in the design, but Xenophon would not be able to progress as much as he hoped. Eventually, Angel returned out of his exile thanks to Xenophon's apprentice Sharle Inocencio and the two inventors renewed production once more. Stripping the design completely and working from the ground up, the device was finalized and christened as 'vertical maneuvering equipment.'

Versions
Known predominantly as 'The Device', it was not until much later that the gear was officially called the vertical maneuvering equipment. As it went through production, there were several iterations made since its conception:
 * Initial/prototype - The first version of Angel's device was rather large and bulky, with the user wearing it on their back much like a backpack. The control mechanism was initially along the lines of a grappling gun and designed in the shape of a pistol. Due to it being a prototype design, no weapons were initially designed to compliment it; although Angel would later use a small dagger made from iron bamboo.
 * Secondary - Angel began working on the second version of his device shortly before his exile, with Xenophon taking over in his place. Reducing the size and weight considerably, he managed to convert it to two boxes worn along the sides of the user and modified the control mechanism to be more easily used one handed. Also, Xenophon would include a large sword made of iron bamboo so the user had a means to protect themselves in combat.
 * Final - The final version of the device that would later become the vertical maneuvering equipment was made through the combined efforts of Xenophon, his apprentice Sharle Inocencio and Angel, who returned from exile. The device was reworked from the ground up, with the primary housing moved to a small compact device worn along the back and gas canisters that powered the device were worn along the sides. In addition, the sword and control mechanism were combined into one so the user could have even more flexibility and the boxes along the sides were changed to hold spare replacement blades.