One feeding device that the squirrels that the squirrels are rarely tempted to assault are the mesh bags made of cotton or synthetic fibers. They are not very interested in the feed, thistle, that is exclusively offered in those bags for the smaller birds.
The time honored, or traditional, device is know as the hopper. Sadly few of them have any defense against the acrobatic feats the squirrel is known to perform for the prize he, or she seeks.
Another problematic device is the platform feeder. In the past its defenses were poor to nonexistent. Today though measures have been taken to rectify the situation. Meshes composed of chicken wire have now been placed over the seed container to stop larger birds and squirrel paws from snatching the feed that is not theirs.