New regulations, aimed at reducing the level of polluting emissions released into the atmosphere, are forcing automotive fuel systems designers to upgrade from materials like Nitrile rubber (NBR) to higher performance elastomers. Viton is the preferred material, capable of meeting low permeation requirements, high temperature resistance requirements and offering good low temperature flexibility and sealing performance. Viton A types have historically been used in such upgrades since they offer significant improvements in heat and permeation resistance over hydrocarbon rubbers like NBR. The Viton AL family of polymers provide the same advantages as Viton A types with the additional benefit of improved low temperature flexibility. The AL family will become the future standard replacement material in upgrade cases for fuel systems as they offer the best balance of all properties at standard fluoroelastomer cost.