Metaglas from L. J. Star is a fused sight glass said to be proven in thousands of installations around the world. Unlike some other sight glasses, the company says, it uses borosilicate glass, rather than less durable similar glass material that doesn’t carry the same level of safety and performance certifications for extreme temperatures and pressures.
Since it was developed in the 1970s, Metaglas has been known as the safest sight glass in the world. A number of chemical and manufacturing companies collaborated to create Metaglas, and to establish the standard with which it complies and by which all other sight glass is measured, a standard now called DIN7079.