Plastic Step Chocks from American Rescue Technology are made of low density, high impact, recycled plastic.  They will not crack or splinter and are resistant to many chemicals, oils, and gasoline.  These step chocks are lighter than wood and will not absorb fluids.  They are resistant to blood borne pathogens and unlike wood can be sanitize and reused.  The steps are angled back to give a level surface when used with wedges.