The air permeameter apparatus measures the permeability or conductance of an (undisturbed) soil sample. Air permeability is the property of the soil pore system allowing air to flow through. Generally the pore sizes and their connectivity determine whether a soil has high or low permeability. Air will flow easily through soil with large pores and good connectivity between them. Small pores with the same degree of connectivity would have lower permeability, because air will flow through the soil more slowly.