Montauk Black 12X24 Gauged Slate Tile are available in a wide variety of tile sizes and has low variations and veining of blacks and greens.It is available in gauged, honed and natural finishes and recommended for exterior projects in climates with no freezing temperatures for ...Montauk Black 12X24 Gauged Slate Tile are available in a wide variety of tile sizes and has low variations and veining of blacks and greens.It is available in gauged, honed and natural finishes and recommended for exterior projects in climates with no freezing temperatures for flooring and walls.This product has a Natural cleft surface and due to the clefts on the surface it will not have an even thickness. This is perfectly normal for this product and that is what is the beauty of this tile. The back of this tile is gauged to enable installers to make the work easy while installing.