The Air permeameter apparatus measures the permeability or conductance of an (undisturbed soil) sample. Air permeability is the property of the soil pore system that allows 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 with good connectivity between them. Small pores with the same degree of connectivity would have lower permeability, because air would flow through the soil more slowly. The air permeability is besides a function of soil texture and macro-pore volume and connectivity, also a function of the matric potential and water content, respectively, because continuous macro-pores which normally would conduct air become more and more water filled with increasing load, depending on the soil and initial water content