Grab bar was great and very secure but I had one hard time installing it on a fiberglass tub due to the space from wall to tub.  I had to buy a special adapter for the wall.  The fiberglass tub initial install didn't have a 2X4, or 2X8 horizontal stud to attach grab bar.  I used this: Keeney PP19000 Solid Fiberglass Shower Grab Bar Backer and Mounting Kit for Bathtub Safety, White (about $30, but well worth it). Anyway, the adapter was difficult to work with but was the best solution for the space problem between the tub and wall. None of this was the fault of the Moen grab bar but the tub manufacturer.