Berryman 4-Step Profession Air & Fuel System Maintenance Kit (part #2640) is safe for all materials of construction in your fuel system.   The Emissions Pass Protection (part #0212) cleans intake valves and fuel injectors or carburetor(s) in order to idealize fuel/air ratios and restore the factory injector spray patterns. In turn, this helps control the products of combustion (as well as improving idle, acceleration, and overall drivability). Additionally, the 0212 contains an additive that helps further reduce emissions. It’s the presence of this additive that necessitates that the emissions test be performed while 0212 is still in the fuel.