Because RMG uses a flux-based algorithm for identifying important species and reactions, the reactor conditions used to generate a model directly affect the conditions at which the model is applicable. Previously, the recommended approach for building a model applicable at a range of conditions was to define multiple reactors spanning the space of conditions of interest. For example, if the goal was to develop a model valid for temperatures from 1000 K to 2000 K and pressures from 1 bar to 10 bar, the user may need to define a dozen reactors with all combinations of T = {1000, 1200, 1400, 1600, 1800, 2000} K and P = {1, 10} bar. This can be bothersome to the user, and risks missing important chemistry which may occur in between the chosen points.