A low viscosity, fully hydrogenated hydrocarbon acrylonitrile ter-polymer (less than 1% residual doublebonds), with low mould fouling properties, designed for applications requiring good flexibility at low temperature, superior resistance to heat, ozone and good resistance to non – polar hydrocarbon fluids. Low viscosity AT - technology provides a broad processing window, low mould fouling and the potential for higher filler loads compared to standard viscosity HNBR types.