Besides being highly effective against the squirrels, this 'Royal Wing Squirrel B Gone' feeder has excellent tension-adjustability to keep even nuisance BIRDS like starlings and grackles from devouring huge amounts of feeder's contents (set it's 2 tension-springs into the HIGHEST of 8 holes holes at base...4 for for each side/spring). Or, if you wish to discourage ONLY the squirrels, then connect springs into the LOWER of the 8 holes (thus, you have 7 tension settings in all). At the lightest tension, only a SINGLE starling alighting onto a perch MAY be able to get a morsel now-and-then with persistence but the weight of TWO of them will shut all 6 ports off completely (however, then, only two SMALL birds can dine at a time comfortably before intermittent closure with a 3rd one). Just increase tension from there to your liking (feeder's 6 ports close immediately when a squirrel grabs onto its side at ANY of its 7 tension settings). I self-measured and confirmed that this 'Royal Wing Squirrel B Gone' feeder's capacity regarding dense, mixed-seed, is 8 cups (equaling 2+1/2 pounds). NOW, I can provide the small (and ONLY the small birds) with the best and most savory, expensive, quality seed/nut mixtures without those greedy flocks of nuisance-birds consuming it all within hours!

Does NOT keep squirrels or large birds out. These feeders are strong, look nice and hold a large amount of seed, so you don't fill as often, but face it, squirrels should run for President...they can figure a way to get away with anything.