In the United States federal law does not dictate any container requirements for cremation. Certain states, however, may require an opaque or non-transparent container of all cremations. This can be a simple corrugated-cardboard box or a wooden casket (coffin). Most casket manufacturers provide lines of caskets that are specially built for cremation. Another option is a cardboard box that fits inside a wooden shell, which is designed to look like a traditional casket. After the funeral service, the box is removed from the shell before cremation, permitting the shell to be re-used. Funeral homes may also offer rental caskets, which are traditional caskets used only during the services, after which the bodies are transferred to other containers for cremation. Rental caskets are sometimes designed with removable beds and liners, which are replaced after each use.