Bonetti level gauges spare glasses bont sight glasses for level gauges sizes: pn 6 to 420; ansi 150 to 4500 materials: carbon steel, stainless steel, hastelloy, monel, nickel, titanium, other special alloys, plastic materials types: tempered, toughened, hardened, prestressed, extra hard applications: - borosilicate glass is suitable for many application features: - have chemical and physical properties - chemical resistance due to heat treatment: hydrolytic resistance.