revaill:

The Three Dimensional Maneuver Gear (立体機動装置 Rittai kidō sōchi?), also called Vertical Maneuvering Equipment, is a set of gear developed by humans that allows great mobility when facing the Titans in combat. 
The gear allows the user to fight in a 3D space as opposed to a 2D one. The gear itself takes the form of a body harness that encompasses much of the body below the neck. Though using it will allow a skilled user great mobility, it carries a large risk of overtaxing the user's muscles, thus special physical conditioning is required to use this gear.
Some tools involved in the apparatus include:
Handgrips 
Piston-shot grapple-hooks
Gas powered mechanism
Iron Wire Propeller with Plug in Blades