So in this case, we have a pair of alleles. But in this case, we do not have a pair of alleles because our male only contains one X. And it's the X chromosome that carries those sex link genes. So if our individual is uppercase B, that means they won't be colorblind, but if they're lowercase B, they will be colorblind. And this type of scenario is called hemisiagus. Hemisiagus means we only have one of the X chromosomes and not two.