I can tell you right now that those don't work at all. We've got a few on our feeders with NOTHING else around them and the squirrels still get on them. They only work if you have a single feeder/pole within about 10 feet of each other. Those little fsckers pull some ninja-esque moves jumping from metal pole to metal pole to get around them. It's entertaining to watch but it can get expensive since when they get up there they eat their fill which can sometimes be 1/6th to 1/5th of the feeder at a time.