I originally gave it a star because there was a problem with the propellers when it arrived and as a result it didn't fly. During the inspection, I noticed that the propellers were incorrectly adjusted during assembly at the factory. There are propellers marked "A" and propellers marked "B". Due to poor quality control, 3 "A" bolts were installed and only 1 "B" bolt. Since additional propellers are supplied in case of failure, I was able to replace an "A" propeller with a "B" propeller. Now it flies very well. It's amazingly durable. And it flies for a long time. So I'm changing my rating to 5 stars.