In me it never had a result. Yes, the device works properly, however it never managed to mix the yolk with the egg white. I literally tried it on 15 eggs, which were at room temperature and not in the refrigerator, and with an effort of over 5 minutes. In the end, I adapted the top part (the one that goes inside the egg) to an electric drill (with a patent) and tried it even like that. Still, the yolk did not mix with the egg white. Either the eggs I chose are some particular unknown variety with the main characteristic that they do not mix, or the device simply does not do the job.

Whatever works, works. However, it requires the eggs to be small, out of the refrigerator, and to pull it about 30-40 times with force. Taking into account the time it takes to put in and take out, you need a minute for each egg. I also have concerns about how long the string will last. As for the taste, personally I didn't see any improvement. If anything, it seems worse than a regular boiled egg. I won't use it again. My humble omelette is much better and much faster...

It's really awesome that it mixes the yolk with the white, the egg comes out somewhat grayish in the end, and the taste is superb.
The instructions are very simple and give the desired result. The little one finally eats yolk, regardless of initially being slightly bothered by the slight difference in taste. The only thing that requires attention: the eggs must be medium to small in order for the internal swirl on the egg to close well and be able to be shaken as intended.
Excellent purchase!