A burial vault (also known as a burial liner, grave vault, and grave liner) is a container, formerly made of wood or brick but more often today made of metal or concrete, that encloses a coffin to help prevent a grave from sinking. Wooden coffins (or caskets) decompose, and often the weight of earth on top of the coffin, or the passage of heavy cemetery maintenance equipment over it, can cause the casket to collapse and the soil above it to settle. Description and usage The burial vault or burial liner is designed to prevent the weight of earth or heavy cemetery maintenance equipment from collapsing the coffin beneath. Coffin collapse will cause the ground to sink and settle, marring the appearance of the cemetery and making it harder to maintain. Burial vaults originally emerged as a means of ensuring that grave robbers could not easily access a coffin and remove valuables, clothing, or even bodies from the coffin. Early vaults were made of wood (the "rough box"), although by the middle of the 1800s brick, iron and later steel vaults were used. By the late 1800s, the fashion of burying the deceased with jewelry lost favor. However, the value of burial vaults in ensuring that the ground did not settle over graves was seen, and burial vaults began to be more widely used. By the early part of the 20th century, concrete (and, later, reinforced concrete) vaults became more common. Although quite commonly used in many industrialized countries, the burial vault is very much a funerary item used almost exclusively in the 20th century. In the United States, the burial vault was largely unknown until the 1880s when the L.G. Haase Manufacturing Co., which owned a cemetery in Illinois, conceived the burial vault as a means of adding a product line to their funerary sales. As late as 1915, only 5 to 10 percent of funerals in the United States used a burial vault or liner. In the 1930s, company owner Wilbert Haase, who had an interest in Egyptian mummification, began promoting the sealed (or "waterproof") vault as a means of allegedly protecting the body from water, microbes, and vermin. The Haase company later purchased several plastics companies, and began manufacturing plastic burial vaults as well. The company dominates the American burial vault market today, with about 12 percent of all vault and liner sales. A burial vault encloses