The first chickies i ever got were sexed via this method and all 3 were 100% guaranteed to be girls. Turns out i had 2 boys, 1 girl! LOL! The bloke was so confident in his method he said if they turned out to be boys he'd take them back and swap them! Well phoned him to say i had two roos and he just would not have it! They were definitely girls! If i gotten eggs from those 2 i would have eaten my cat! LOL!