Gas can be delivered through one of two air bearing types—those with orifices or those made from porous media. In an orifice bearing, pressurized air is supplied through precisely sized holes placed on the bearing surface. These holes are typically combined with grooves to distribute the pressurized air evenly across the bearing face. The drawback of orifice delivery is that air loses pressure and creates pressure gradients in the air gap as it expands away from the orifice or groove. Porous media air bearings allow air to be supplied through the entire surface of the bearing, due to millions of holes in the porous material. Thus it acts as an ideal air bearing supplying air pressure equally across the face of the bearing. Air Bearing Pressure Profiles