Correction factors from measurements with HFI to what would be observed by SPIRE, K_{HFI− > SPIRE} (Eq. (2)), for MBB spectra (Eq. (3)) with a range of temperatures, T_BB, and emissivity indices, β, at the two HFI frequencies. We decreased the resolution along the temperature axis by a factor of 10 compared to the tabulated values to a step of 1 K. The anti-correlation between T_BB and β can produce the same MBB SED shape across the bandpass and, hence, the same correction.