Squirrel Buster Plus
The Squirrel Buster Plus keeps out squirrels and some nuisance birds by using an adjustable weight mechanism that closes access to the seed. Features seed tube ventilation to keep seed fresher, adjustable perches and attachable cardinal ring. Disassembles for cleaning, is chew and rust-proof, with a 3 quart seed capacity and Lifetime Care. It was voted BEST squirrel-proof bird feeder by Popular Science.
Here are some things to check/implement with your Squirrel Buster Plus Feeder to make it truly squirrel-proof for adult red and gray squirrels (please note that juvenile red squirrels and chipmunks can sometimes access seed due to their light weight):
1) Observe the manufacturer's stated installation clearances, e.g. install the feeder with 18" of clearance between top of feeder and the branch it is hanging on, 18" of clearance from launching points below the feeder, and 18" radius of clearance around the sides of the feeder;
2) Don't exceed the maximum level of seed, otherwise the shroud will not be able to close properly. Cover must be latched to prevent squirrel access and squirrel damage.
The Brome Bird Care website has great illustrations of these parts: https://bromebirdcare.com/squirrelbuster-plus/