MAXOS clear sight with definite safety Whether in the chemical industry, the oil industry or the power supply sector, Maxos safety sight glasses are proven and used all over the world whenever visual inspections under extreme temperature or pressure conditions are required in steam vessels, pressure tanks or pipeline systems. The high safety level is secured by special borosilicate glass of high chemical durability, exceptional purity and homogeneity. Along with a low thermal expansion, which is typical for borosilicate glass, thermal pre-stressing (tempering) creates a particularly high resistance to sudden changes in temperature.