Yes, it works! I put it on the Poser 4 boy. The collar opens perfectly, and nothing particularly weird happens when I pose him. It's tempting, but I still think it would be more sensible to go with Wardrobe Wizard because of what I pointed out about being able to use my V4 stuff on the Poser people (so I would get more use out of it.) Still wish I could figure out the fitting room, though.