sight glass material:304/316L size:1" to 4" STD:3A,SMS,ISO,IDF Product Name: Sanitary Sight Glass Type: Welded ends Material quality: SUS304, SUS316L, 321,304L, 316Standard: DIN,ISO,SMS,IDF,3A, GBSpecification: DN25-DN100 & 1"-4", applied to the stainless steel pipeline system Medium: Beer, Dairy, Beverage, Pharmacy, Food, Water, Cosmetic