When determining the length of a grab bar needed, keep in mind that the overall length of the grab bar is about 3 inches longer (3.125 - 3.25 inches depending on the style of bar) than the name of the bar. So a 48 inch grab bar would measure about 51 inches end to end with the points for attachment 48 inches apart.
48 inch grab bars are generally used in oversized bathrooms or in commercial bathrooms that require a minimum of a 42 inch bar adjacent to the toilet. While installation into studs is always ideal, state of the art Snaptoggles and Secure Mount Anchors can make any installaltion in a hollow wall easy even if you can't locate the studs. All of our 48 inch grab bars meet or exceed ADA guidelines for safety in the bathroom.