Insulation bricks are commonly used in electric and gas kilns where there is minimal abrasion against the lining of the kiln. This is due to the bricks being lightweight and not very dense. 23Grade bricks can withstand a maximum service temperature of 2300 degrees Farenheit, 26GD, 2600 degrees and 28GD, 2800 degrees. They can either see the hot face of the kiln or be used behind another layer as insulation. Technical Data sheets are available on request, or if you have any questions please let us know and we will be only too glad to help! We can also supply bricks cut to specific drawings, please enquire if you have a special shape?