Drag timescales over the effective radius a_eff dependent on the grain model (BA, BAM1, or BAM2). Left panel: gas drag timescale for different gas densities n_gas for all grain materials. The gas temperature is at a constant value of T_gas = 100 K. Center panel: IR drag timescale for the CA grain material for different dust temperatures T_dust. Right panel: same as the center panel, but for the SC grain material.