These Grav-Cutters are large
surfboards airboards that is used by Neoteks from House Van Saar in Necromunda, who often favour either untested or dangerous tech, of which the Grav-Cutter is one of them.
Again, how the fuck these guys manage to get a hold on these technologies without triggering the Adeptus Mechanicus, we have no idea. Seriously, where the proverbial fuck are these gangsters getting that shit from? Anti-grav technology is already a tough commodity to manufacture even among esteemed Forgeworlds, let alone a flying surfboard. And this was before Grandpa Smurf woke up mind you, without any of Uncle Cawl's wacky hijinks. And let's not get into those energy shields.