Mystery Electronics backboxes are UL Listed and conform to all applicable N.E.M.A. Standards. While locally available boxes may seem acceptable as substitutes, there are differences in certain critical dimensions. For a fast and easy installation and to avoid costly onsite rework, the user is strongly cautioned to use only Mystery Electronics backboxes. They are proven to be the lowest cost alternative. They are also recommended for raised wooden floor or hollow wall construction, though site conditions may make them optional.