A flat flat bronze grave marker with vase in section 74 of Mount Olivet Cemetery in Washington, D.C., in the United States in 2014. This section of the cemetery is "perpetual care", which means that headstones must be set flush with the earth. This allows for easier grounds maintenance, as a riding grass mower may pass easily over the graves and no special equipment (such as manually-wielded string trimmers) or labor is needed. Various kinds of headstones -- bronze or granite -- may be used. Some more expensive headstones have a slot into which a brass or bronze flower vase may be temporarily placed. When not in use, the slot is usually covered by a brass plate.