this kind of silica submerge nozzle has high strength, good corrosion resistance and termal shock resistance, it'scompetitive price can reduce your production cost. the chemical and physical properties is follows: Item indexCRS QRS SiO2 % 99 99 Apparent porosity % 19 18 Refractoriness 1750 1750 Bulk of density g/cm3 1.82 1.84 C.C.S. Mpa 39 39 Thermal shock times 30 30