The ATR crystals for the SplitPea, Meridian and VideoMVP are offered in several different materials to accommodate a variety of spectral ranges, sampling conditions, and penetration depth requirements. All are mounted in chemically-resistant holders. The Si and diamond ATR crystals offer highest chemical resistance. The Ge and Si ATR crystals feature a small sampling volume due to their low penetration depth and 250µm diameter sampling area. The ZnS, ZnSe, and diamond ATR crystals feature a somewhat larger sampling volume with their deeper penetration depth and larger, 500µm diameter sampling area.