Transparent Gauge Glass DIN 7081（seventy eighty one） is also named Flat Gauge Glasses and Plain Gauge Glass.Its typical characteristic is two-sided polished and tempered and made from specific glass material types-commonly 4.2（four point two） expansion borosilicate glass which results in products characterized by high mechanical strength and high resistance to alkalis, acids and condensates.

It can be used with all media at service conditions up to 4MPa and temperature up to 400 °C.（four hundred degrees celsius）