It's always a good idea to keep spares for your toys and the PicooZ is no different. If you happen to break both of the tail rotors that come with the helicopter you're going to be stuck with a really great toy that's absolutely useless. That's why you need to keep a few packs of these around to keep you flying, and they are the genuine Silverlit tail rotors so you know they're quality. They will also fit many of the other similar micro helicopters on the market.