Borosilicate 4.0 fire resistant glass: the maximum fire resistance time is 3 hours, ultra low expansion coefficient small specific gravity, more than 8% lighter than ordinary soda lime silica glass ultra clear, light transmittance above 92% thickness range: 4 15mm maximum size: 4800*2440mm can be used in fireproof curtain walls, partition walls, platforms, day lighting roofs, smoke proof vertical walls, railings, doors and windows, elevator shafts, rail transit platform screen doors, rail locomotive doors and windows and other fields.