Plastic methylmethacrylate ball pestles are intended to be used with SpectroVial® polystyrene vials. By comparison to metallic vials and their corresponding ball pestle materials, plastic is relatively soft and not very effective in the comminution process. Its principal application is for blending sample material substances or for comminuting soft samples. Stainless steel ball pestles are principally used for comminuting relatively hard sample substances in annealed stainless steel and SlipFit® stainless steel SpectroVial® comminuting vials. Tungsten carbide ball pestles in combination with SpectroVial® titanium carbide vials share hardness similarities and much more effective grinding media for extremely hard and difficult to grind samples.