Level Gauge Glass, Optical Glass, Bulletproof Glass manufacturer / supplier in China, offering Durable Circular Sight Glass Fittings for High-Heat Applications/Circular Sight Glass Fittings Type 390, Tank Sight Glass Type 320 for Vacuum Applications up to Pn10/16- Lumiglas, Tank Sight Glass Type 318V for Vacuum Applications up to Pn 2.5 - Lumiglas and so on.