3M Extended Range 5' Disk Markers are not for direct buried applications and provide an easy, accurate method of locating flush mounted facilities which become covered by backfill or other obstructions, such as snow or vegetation.The 3M Disk Marker provides an easy and accurate method of precisely locating flush mounted facilities, which become covered by backfill. The four inch disk marker is easily fastened to the underside of non metallic lids or covers over flush mounted facilities, such as hand holes, manholes and other grade level enclosures during construction and maintenance. Disk Markers are not intended for direct burial.