Metal pole with bird feeders on it..how to keep squirrels from climbing up and eating all food?

I have put vaseline on pole..but it wears off too fast...Metal pole with bird feeders on it..how to keep squirrels from climbing up and eating all food?
This is from Birds and Blooms Mag. Simply drill a hole in bottom of a plastic planter and slip it on the pole top-down below the feeder. Then sit back and watch as the squirrels try to climb the pole. If you can find this magazine their are quite a few other ideas to try.Metal pole with bird feeders on it..how to keep squirrels from climbing up and eating all food?
they make a device i'm not sure what it is called but it looks like the thing they put on a dog when it has wound to keep it from chewing on the bandages it acts as a obstacle they can't get around to get to the bird feeders.
over the birder feeder drill a hole in a pie pan and put it through the string over the feeder. when the squirrel jumps on it it wiil fall of.
they make squirrle baffles. they are these large metal or plastic funnel looking things that go around a bird feeder pole that keeps them from climbing to the top. about 20 bucks or less. depending..