Plastic | Dimensions -- Set of four 3 inch bed risers with four high-density foam and rubber pads (actual lift: 2.6"). External: 4.2"x4.2"x3.3". Internal: 3.2"x3.2"x0.6". Creates under-bed storage while protecting floors and furniture. | Heavy Duty Durability -- Scratch-proof non-slip plastic construction. These bed risers heavy duty support 2200 lbs. Use as risers for bed frame only with proper installation. | Stackable Design -- Lifts furniture 3 inches individually. Stack for 6 inch elevation – perfect dorm bed risers. Function as bed lifts risers for adjustable height. | Primary Application -- Designed specifically as bed frame risers for beds. Ideal bed risers for dorm twin xl storage. For other uses, verify installation safety. | Secure Space Creation -- Elevates beds furniture to create storage space. Non-slip pads ensure safety while maximizing space.