Wide bandwidth Bragg cells are of extreme importance in many acousto-optic applications. The proper choice of material and crystal orientation for the Bragg cells is critical for maximizing the performance of such a system. The physical properties of importance in the design of wide bandwidth Bragg cells of such systems will be reviewed. The advantages and disadvantages of the best currently available acousto-optic crystals will be evaluated with regard to these physical properties. Methods for selecting the optimum material and crystal orientation for a given bandwidth will be discussed.