Product details:

The ingenious design of this cheery red feeder allows birds to dine in comfort. When a squirrel tries to get to the seed, however, its heavier weight triggers the spring-operated perch, closing access to the seed. You can even adjust the weight setting to discourage large birds, saving seeds for smaller songbirds. An easy-open, tamper-proof latch provides you easy access for filling, but foils hungry squirrels.