The Rocket Fuel widget, or officially Sarge's Experimental Rocket/Turbojet Fuel, was introduced in the V2 Vengeance update in conjunction with the sale of the Rippin' Rocket and Thor's Turbojet outfits for battlefunds. The Rocket Fuel widget only works with one of the jetpacks from the previously mentioned suits is equipped, much like the parachutes in the Royal and National Paratrooper sets. Another fuel came with the Dead Space suits. Third fuel with the Metallo set.