Comparison of HI parameters derived by the Cosmicflows and ALFALFA collaborations identified by the subscripts CF and α, respectively. Only galaxies available in the α40 release are considered. Left: comparison of the S/Ns, S/N^CF and S/N^α. Right: comparison of the line widths and . The difference is represented as a function of the S/N, S/N^α. The black dotted line represents the threshold S/N^α = 15 discussed in the text. Data above this threshold can be fitted to km s⁻¹, which is represented by a solid red line.