Surfaces Surfaces Concave Concave surface is suitable for general and anti-slip purposes. Smooth Smooth surface is smoothed off after surface finishing process. Solid Solid gratings are produced by combining one side smooth or sanded composite panel with smooth surface gratings. Sanded Gratings can also be provided with a sanded surface applied with resin for achieving higher anti-slip quality. Sandwich Panel Sandwich gratings which are solid on both sides. Chequered Plate Effect Chequered plate effected gratings are another solid variant.