Squirrel proof

I have tried many ways to stop the squirrels eating the bird seeds. I have six- eight squirrels now, so purchased a squirrel buster and hung from tree with an 18inch plus length of chain. Which I read about whilst looking for deterrent. This length does not allow them to reach the feeder whilst hanging onto the branch with their hind feet plus they are unable to climb down the chain. Put a smaller mealworm feeder alongside, this also deters them. So far so good.