The Poly Sight Glass is used in-line with your transfer hoses so you can observe the product moving through the hose. See any debris or know when your tank is almost empty. Can be used with both fuels and chemicals including corrosives. Fittings are all stainless steel Dixon® brand and the female coupler is the EZ Lock handles. Hose is a chemical grade, non-collapsible hose with a wire inside the poly material. This wire, along with the stainless fittings insures that you have continuity especially when pumping flammable liquids.