The B stands for "Baldy." The difference between a SHTCT and a SHTCTB is that the latter has no spots on the top of the head. Sprocket used to be a SHTCT, because she had one spot above her left eye (we called it her beauty spot). But after a shed a month or so ago, it disappeared, so now she's a Baldy as well. Hope that answers your question! If you look in my albums you will see the spot on her head in at least one of the pictures.