This specification covers rigid polyurethane foam blocks or sheets recommended for use as a standard material for mechanical testing using orthopedic devices and instruments. Although the physical properties of the foam are in the order of those reported for human cancellous bones, these materials are not intended for implantation into the human body. All materials should conform to the specified quality of appearance, dimensional stability, and composition, and values of void content, compressive strength, compressive modulus, shear strength, shear modulus, and screw pullout.