Over the 2 years I've been feeding birds in my backyard, I've been through several different "squirrel proof" bird feeders, and the squirrels have managed, eventually, to break into them all. This one is the BEST I've had - well worth the price. Having had this feeder for several months now, and observed the squirrel's behavior, I can now list the PROS of this feeder: 1. The spring loaded action PLUS no foothold for squirrels at the bottom: You won't realize how well this feeder is designed if you haven't seen the antics of really smart squirrels and less well designed feeders! My previous spring-loaded feeder had a fatal flaw - it had a foot-hold at the bottom which one particularly smart fox squirrel figured out how to use to his advantage. Using his feet at the bottom, and pressing up with his hands at the top, he was able to hold onto the feeder WITHOUT triggering the spring-loaded action, thereby keeping the feeding windows open! This feeder has NO foothold at the bottom, and the smart fox squirrel can no longer "cheat" the system! He has tried, but failed every time! (He's very disappointed!) 2. The spring loaded action design itself: This feeder's spring loaded action works MUCH more cleverly than my previous feeder. Instead of having small flimsy springs on the outside (which kept slipping off after the squirrel's boisterous break-in attempts, and getting weaker and weaker), this feeder has a very sturdy plastic, spring-loaded rod going through the middle of the feeder on the inside! This is totally protected from squirrels, and therefore doesn't slip off or weaken over time. The spring loaded action also keeps larger birds, such as grackles, off the feeders. This is especially useful if, like us, you sometimes get "grack attacks" in the summer, with 20 or more grackles all trying to storm the feeder. One grackle alone can feed unhindered. But 2 or more grackles on this feeder are too heavy and close the feeding windows. This makes the grackles give up after a while and go elsewhere, allowing the smaller birds to get back on. 3. Secure metal protection around the feeding windows: I'm very happy with the sturdiness of the metal around the feeding windows. My previous spring-loaded feeder had flimsy, detachable metal bars around the feeding windows. Once the smart squirrel had over-ridden the spring loaded action, he was then able to knock these detachable metal bars off and chew through the plastic, widening the feeding windows for his access! This feeder won't let the smart fox squirrel override the spring-loaded system anyway, but if somehow he did, I have no worries about him knocking off the metal around these feeding windows - they are far more sturdy, securely locked down, not removable, and go around the entire feeding window. 4. The securely locking LID: This is perhaps the BEST feature of this feeder! My previous spring-loaded feeder did not have the securely locking lid that this one has. It had a lid with a small spring that loosened every time I had to fill the feeder until the spring eventually broke. Once broken, the squirrels easily managed to prize the lid off, then dive into the feeder! (They were also then able to chew the plastic around the top of the feeder, widening their access!) This locking lid works by having 2 metal buttons, one on each side, that you have to push simultaneously with your hands, to open the lid. These are sturdy and I can't imagine them breaking or loosening. They are also impossible for squirrels or anyone other than a capable human to manage. (They were even a bit tricky for me at first, but after a bit of practice, I've mastered them!) 5. Unchewable metal cage: So far, this is definitely holding up. The smart squirrel (that used to override my previous feeder's spring-loaded action) has been trying to chew through the metal on this one. I can see teeth marks and scratches on the surface of the metal, but that's it. He hasn't been able to do more than scratch it. He's very frustrated! 6. Unchewable plastic: This hasn't been put to the test yet, (as the squirrels haven't broken through the other features yet), but the plastic on the inside of this feeder, under the metal cage, looks a TON sturdier than my previous feeder. This product does claim that it is chew-proof. Seeing how impressive all the other features are, I'm confident this is true too. I don't think the squirrels will ever be able to prize the securely locking lid off this feeder, or override the spring-loaded feature, or chew through the metal cage. However, let's say I accidentally left the lid unlocked, (which hasn't happened yet, but, hypothetically...) I feel sure that the squirrels wouldn't be able to do what they did to my previous feeder - i.e. chew the plastic around the top of the feeder, widening their access to the food. 7. Proper drainage at the bottom, keeping bird food dry: This is a really good added bonus. My previous spring-loaded feeder had a poorly designed bottom. It had inaccessible spaces at the bottom, leaving bird seed to gather there, uneaten. It also had no drainage holes. Inevitably, this bird seed got damp and moldy and was difficult to clean out. This feeder has a very well designed bottom. It has no inaccessible spaces - the birds can get to all the seed at the bottom, leaving no waste. It also has drainage holes at the bottom, allowing moisture to drain out, keeping the bird food drier for longer. 8. Well designed slanted roof lid, keeping bird food dry: Another bonus feature. My previous spring-loaded feeder not only didn't have a securely locking lid, it also had a FLAT lid, where rainwater and snow could gather! This feeder has a slanted roof lid, allowing rain to run off, and away from the feeder, keeping the bird food drier for longer. It also has a very small, cone-shaped piece of rubber above the lid, on the wire, which prevents rain water wicking down the wire and dripping onto the lid. Fantastic little detail! 9. Funnel for filling the feeder: Another nice bonus. I'm very glad they provided a funnel to go with this feeder. With the secure locking lid, it would be a bit tricky to fill the feeder without the funnel (especially if your feeder is tied to the tree branch as mine is). The funnel is sturdy and specially designed to fit the feeder, keeping the spring loaded rod in the middle out of your way, as you pour the food in. It does what it's supposed to do, i.e. prevents seed spilling out as you pour, and therefore making filling so much easier. I haven't got any "CONS" to list at all for this feeder. Even the slightly more expensive price seems very fair. It's a very good investment, well worth the price. If I hadn't known how much grief the squirrels were going to give me with my previous (cheaper) feeders, I wouldn't have bothered with them, and would have gone straight for this one in the first place!