This product is exactly what we use in all of our expansion tank delete kits and allows you to add a fill location to your engine. Generally most will locate this into their upper radiator hose for a location to burp the coolant system and serves as the coolant fill spot. We use and sell these with most of our GM/GMC truck turbo systems and this is a required item in most cases since our radiator line kit is designed to be used with this. The construction of the fill port starts with a block of 6061 aluminum and end up with a final product like you see. This is a very high quality piece and we alway strive to make it better than what else is available. Our hose barbs are turned down to the specific diameters required and then machined for an 0-ring seal. This allows for a leak-free application, none of the other manufactures are doing this. The coolant system will build pressure so its important to have a good seal to ensure coolant isn't sprayed all over your detailed engine bay. Ohio Sales: Subject to 7.50% sales Tax in the State Of Ohio Shipping: Free to all 50 USA States