Adjustable bed riser set creates extra under bed storage space for shoes, luggage and boxes. They're also useful for raising the head of a bed for breathing or digestive reasons. Molded plastic risers securely lift, hold and support bed legs or casters off floor. Recessed wells in each assure that your bed won't fall. You get four 3 raisers and four 5 raisers. For maximum height, stack them to create 8 of total elevation. Holds 1,300 lbs. maximum.