There are both DIN and ASTM standard products which are in our U-PVC Flange Connection Sight Glass product. Our general size range is from 90mm to 225mm. There are both DIN and ASTM standard products which are in our U-PVC Flange Connection Sight Glass product. Our general size range is from 90mm to 225mm. (including 225mm) For DIN standard, the operating pressure is PN16 including 140mm, the operating pressure is PN10 from 160mm. Usage area: Drinking water lines, Pool systems.