3 FT 3M Adhesive Depth Marker 6 Inch x 6 Inch with 4 Inch Lettering Eliminates messy stenciling. Made of a durable commercial-grade vinyl and are pressure sensitive. They are skid resistant which helps prevent slippage. They install quickly and easily, giving you a professional look 3M Stick-on Depth Markers are for above the water line use only!