And that's another thing, the pen holder. Yeah, suuuuper convenient to stick the pen into the brush but it makes no sense. Unless you are marketing it for travel, why bulk up the handle of the brush? It makes it feel like a child's toothbrush. And you STILL would not be able to put it in your carry on because it's a gel and TSA doesn't like you idly handling gels while waiting for your complimentary in-flight drink. Maybe you should have at least made it do that stupid thing where it plays music to distract from how ridiculous the build really is. And shower use? Pft. Unless you like getting gunk stuck up in the brush base, I wouldn't recommend it unless you separate the two and let them dry individually.
End result? If you're going to sell the pen, sell the pen. Do not try to make some lame combo package out of it and mess up the brush in the process. Negative to purchase possibility.