Apologizes in advance if I've missed something obvious.
Was looking at the Hell Knight Signifer as I may be building one soon and I realized that I didn't fully understand how the mask works as a bonded item.
So the Signifer PrC states "This ritual converts the enforcer's mask into his new bonded item, which takes up the head slot. In this case, Hell Knight enforcer levels stack with levels from the class that grants the bonded item for determining what additional magical abilities can be added to the bonded item."
My confusion comes from the fact there is no 'head' bonded item category. Now since which category it's in determines what properties you can give it, it's something I'd like to know before i start coming up with a build.