This city water fill's flange measures 3inch and connects to 1inch threaded pipe on the outside,3/4inch threaded pipe on the inside. The pipe threads are plastic and the outer pieces, plastic in composition. Easy to install and use, it's a terrific alternative to a brass city water fill. When you're on vacation, you need to have access to fresh, clean water at all times. And in an RV, that means having your fresh water tanks filled and ready. In order to get that water in there, however, you'll need a water inlet, such as this city water fill. Don't let your water suffer from a low-quality inlet. Instead, add this model for terrific use and life. Maintenance water tank: The use of the water filling port can keep the RV water tank always have enough water to that there is no restriction during travel. Product length: 77mm Product width 75mm Product screw ring: 20mm Applicable models: Applicable to RVs Colour:Black Material:ABS Size:7.5x7.5x7.7cm/2.95x2.95x3.03 inches Package Contents: 1 x RV Water Fill Inlet Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.