Mine is made of four inch pvc and I still had a problem with it only flowing out a little way into the feeder tube. What I did was change out the 90 to 2 45's and it flows better with not such a tight corner to go around.these feeders work well for a few chickens but if your feeding a lot of birds the feed will not push out more than a foot or so and doesn't allow many birds to feed at a time so there will be some fussing going on while some feed while others wait but they will work it out and it does save food and keep it cleaner.