Working in conjunction with ramps and stakes, these spacers add 4 inches of vertical height to 18-inch and 20-inch load leveler ramps. They are considerably lighter than using wood to add additional height, and will last for many more years. Hardwood must be used on top to protect the aluminum surface. Manufactured in the United States from military-grade aluminum, they are a sturdy, durable choice for achieving the height your load requires.