LAB's segment air bearings.
Segment air bearings are often used to support a rotating shaft. They are also suited for linear guides. Segment air bearings can be found in linear as well as rotational applications. A great advantage is that they can be mounted on a fully supported rod resulting in a stiffer construction.
In large diameter applications they offer a cheap and simple alternative for expensive roller bearings.
More info on LAB's SAB-series