FIRE BRICKS that are made from clay minerals, alumina etc. can withstand high heat, and are used for hot insulation applications like fireboxes, lining furnaces etc. Generally heat-resistant up to 1200 Deg. C. These are to endure high temperatures without cracking or deteriorating. INSULATING BRICKS, also sometimes referred to as REFRACTORY BRICKS, hold strong resistance against extreme temperatures. They are used in kilns, furnaces etc. for very high temperature applications. ACID-RESISTANT BRICKS, which are made from high silica stone and fire at high temperatures. They are chemically resistant and thermally durable. ZIRCON BRICKS: These are also fire bricks, but are made from Zircon and Zirconia raw materials. Used in high temperature applications and equipment. Normal sizes are : 230mmx 115mmx 75mm, 200mmx 100mmx 50mm, 235mm x 112mm x 65mm. CASTABLES: These are also refractory products that withstand high temperatures and retain their composition. They are widely used in boilers, furnaces etc. Dense castable (Castable of various densities), Castable with low cement components (Low cement Castable), Insulation castable are different types.