Kosun Fluid makes all kinds of stainless steel sight glass, Including inline sight glasses, and sight glass for welding to the tanks. Inline sight glass Size from 1” up to 6”. And tank site glass from DN50 - DN300. Material including 304 Stainless steel and 316 Stainless steel. We also accept customized sight glasses. The Sanitary Sight Glasses are designed for sanitary applications used in the food, dairy, and pharmaceutical industries.