I have a Gopro 3 white edition I bought used at a pawn shop for $60. It came with waterproof case with deep back for the included LCD screen. I thought that was a great deal. Anyway, my daughter sent me a couple of backs for the housing. The one shallow back for the camera with no lcd screen fits fine. The shallow back with cutouts on the back is smaller and won't work. What the heck is that for? I was hoping to use that so I can get better sound. Are other gopro housings smaller?