Casco International offers Double Window Sight Glass. Casco International is an ISO 9001 certified company which offers wide range of industrial Investment Castings Valves in steel and cast iron. The Double Window Sight Glass is used for Investment Castings. It features Manufacturing Standard: BS 5351, Testing Standard: BS -5146 and Face to Face: ANSI B 16.10. This sight glass comes in DN 25 to DN 50 size range. It is used in all process handling needs.