Black powder coated aluminum extension. Adding length to your rack with only 500 extra grams. New version without paint on the first 20 cm for easy mounting. Mounting guide: If trouble sliding in the extenders. Use a round or semi round file to take off any welding burrs on the inside of the rack where the two tubes are welded together. Grease it up and test each side of the extension separately to see if they slide in with the desired resistance.