Gtechniq - Car Care Products - G4 Glass Nano Polish - 100 ml Description G4 utilizes consistent nano sized abrasives and a citric acid based cleaning agent to provide fast and agressive glass and ceramic cleaning to remove contaminants that glass cleaners fail to remove. G4 does exactly what it says on the tin. It remove all contaminants from glass or ceramic surfaces which are not removed during normal cleaning process without any damage to the substrate. G4 is easy to use and is exceptionally fast. We recommend using G4 prior to G1 or G5 application on any glass other than on new cars.