Super Fill is a glass hard, inert, hollow silicate sphere. Super-Fill is primarily used to reduce the weight of plastics, rubbers, resins, cement, etc., but also imparts further benefits in many situations. Many of the advantages from the use of Super-Fill, including increased filler loading and improved rheology, are directly attributed to the spherical nature of the material. Cenospheres are unique free flowing powders composed of hard shelled, hollow, minute spheres. A small proportion of the pulverised fuel ash (PFA) produced from the combustion of coal in power stations is formed as cenospheres.