Their insulating temperature stand at from 1 200 to 1 300 degrees centigrade, compression strength 33-55kg/? and density 0.45-0.66g/?.

They are made of industrial wastes from thermal power stations and inorganic composites.

The Heat Engineering Institute under the State Academy of Sciences and the Analytic Institute of Kim Chaek University of Technology have rebuilt an experimental high-temperature furnace by use of the kind of fire bricks, which takes only a half of electricity consumed by the existing ones.

A number of factories, including the Songyo Ceramic Factory, have rebuilt furnaces with the bricks, lowering electricity consumption 40 to 50 percent on an average.

Stoves made with the refractory materials are favored by housewives for their high efficiency.

Insulating tiles have also gained popularity among consumers.