- "Oh, now this is just getting ridiculous!"
- —Felix when fighting Wash upside down
- "We've had worse."
- —Washington in Great Destroyers
Grav Boots are a form of Armor Enhancement that allows the user to release their own form of artificial gravity to the soles of their boots in order to keep balance and attach to surfaces. First appearing in Evacuation Plan, the enhancement is mainly used by Freelancers and certain mercenaries, such as Locus and Felix.
- Washington: Wash first uses his grav boots in Heavy Metal, after he accidentally shuts off the artificial gravity of an Insurrectionist hangar. He alerts his teammates about this and prompts them to activate their grav boots as well. Much later, Wash uses his grav boots while battling Felix and Locus in Great Destroyers, alongside Carolina.
- Carolina: Carolina briefly uses her grav boots in Heavy Metal to fight off numerous Insurrectionists. She then later uses them in order to protect Kimball and the Reds in Armonia, Part 2 and during her fight with Felix and Locus in Great Destroyers.
- North Dakota: North first uses the grav boots in Evacuation Plan to stabilize himself on the roof of the Pelican to fight off enemy missles. He uses them again in Heavy Metal in order to fight off several Insurrectionists, though he isn't seen using them anytime afterward.
- South Dakota: In Heavy Metal, South uses her grav boots to fight off numerous Insurrectionists, though she isn't shown using them afterward.
- Locus: Locus is first shown using the enhancement in Prologue in order to keep himself connected to the Tartarus after Felix activates the ship's purge. He later uses his boots in Great Destroyers in order to prevent himself from falling off a descending platform.
- Felix: Felix first uses his grav boots in Prologue in order to keep himself on the Tartarus after he activates the ship's purge. He then uses his boots while fighting Wash in Great Destroyers.
- The Grav Boots are likely based on the Mag Boots that the SPARTAN soldiers utilize in the Halo franchise, except they make use of artificial gravity as opposed to magnetic fields in order to keep the user stuck to a surface.