H i mass-to-light ratio. The lines indicate the sensitivity limits for a 4σ, 50 km s⁻¹ top-hat profile at 0.5 mJy rms at 17 Mpc (solid line) and 100 Mpc (dashed line). The y-axis is in logarithmic units. Blue squares are late-types, red are S0s and green are unclassified objects. Red triangles are dEs and black crosses are background detections.