Several tortoise keepers bought these years ago and while they did show there was a live tortoise in some eggs, the results for infertility were poor and many keepers opened supposedly dead eggs to find live babies that obviously died due to being opened too early so at the end of the day there was nothing to be gained by using them. Most have gone back to candling and waiting to see what happens. I would not like to disturb incubating eggs to this degree myself anyway, as they are not like birds that need to be turned regularly.