3M's cerium impregnated material is a fascinating variation on their time tested Trizact material. The cerium oxide is encapsulated in tiny microscopic pyramid shapes. When these shapes come into contact with water and and the surface of the pyramids come into contact with the glass, the cerium oxide is released slowly from the encapsulation. The shape of the pyramids provide the necessary friction between the cerium and the glass for the polish.
Since the cerium is being delivered directly to the surface and providing it's own friction, the cerium impregnated belts are highly efficient. They can polish in a fraction of the time it typically takes for a felt belt with cerium slurry to operate. They also are far less messy as there is no cerium slurry to deal with. Only water.
You also do not have to worry about contaminating the belt as you do with the felt belts. Since the structure of the cerium belts is not porous, there's no where for contamination to stick so it flows off the belt as you work and continues to provide a clean easy polish on your work.
It is vitally important not to leave your cerium belt on the sander under tension. Be sure to remove the belt from your belt sander to dry loosely.