Many Northeast Ohio cemeteries require a burial vault to be used over the casket in the ground. A burial vault protects the casket from the weight of the earth as well as heavy equipment that may be used by the cemetery for grounds maintenance. A burial vault also helps keep the grave level, which contributes to the overall aesthetic appeal of the cemetery. Metal vaults utilize an "air seal" concept while concrete vaults utilize a "top seal" or "tongue and groove" concept.