Comparison between FIR total H₂ + H I hydrogen masses, M_FIR, estimated from FIR data, and total H I masses of AGB star CSEs, both in M_⊙. Clear H I detections (det.) are shown as dots, possible detections (pos.) as smaller squares, and upper limits (lim.) as open triangles. Colours indicate different types of variability: red for Miras, black for SR types, and green for L types. FIR masses are based on 60 μm IRAS data or 70 μm Herschel images. The colours of the IRAS data are of a more vivid hue than the Herschel data, such as red vs. orange and black vs. grey. To guide the eye, the three dashed blue lines indicate FIR:H I mass ratios of 100:1, 10:1, and 1:1, respectively.