Transparent glasses are also manufactured from extra-hard borosilicate glass. The surfaces on both sides are finely smooth and ensure optimal transparency. Now we have two kinds manufacturing technique: 1.One is as same with reflex gauge glasses, use molds to make the semi-finished products, afterwards, ground and polish the two side to ensure optimal transparency. By this manufacturing technique, the definition isnt good. 2.The other manufacturing technique is: At first, we manufacture 17mm thickness glass sheet, then cut the glass sheet according the detailed size and polish the side face for the smooth. This manufacturing technique glass is very clear, but the goods cost is higher. It can be used with all media except steam at service conditions up to 6MPa and temperatures up to 260 °C.