Transparent type is also manufactured from "extra-hard" borosilicate glass. The surfaces on both sides are finely smooth and ensure optimal transparency.
A) 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 isn't good.
B)The other manufacturing technique is made of High Borosilicate sheet of 17mm thickness, 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 at service conditions up to 6MPa and temperatures up to 430 degrees centigrade.