Grid markers are precast concrete with a cast aluminum cross hatch set in the top. Grid markers are used to accurately mark the location of graves within a cemetery lawn crypt development which can contain hundreds of burial spaces. They are typically 6” square and 24”-36” long and are set vertically, often times over 100 feet apart. String lines are pulled from one to the other over the cross hatch and measurements are made to a specific grave location. The hole in the top (as seen in the photograph) is where the cast aluminum cap is set in. The cast aluminum cap typically bears the name of the cemetery. Almost all cemeteries use some sort of grid system or lot markers.