Nullify Stack-Its are 4 inch wide x 1 inch tall stackable risers featuring recessed holder tops with fit contours designed to hold in all furniture feet/legs 1" to 3.5" round or 1" - 3.25" square, furniture panels / bases 0.5" to 1.5" wide, and caster wheels up to 2” in diameter x 2.75” width. Not for use with furniture legs, bases or panels outside these size parameters. Each Stack-It riser is 4 inches in diameter and are perfect for raising desks, couches, sofas, beds, tables, armchairs, dressers, and more. Please note stack its are not compatible with furniture feet/legs larger than 3-1/2” Round in diameter or 3-1/4” Square in width, furniture panels/bases larger than 1-1/2” wide, and caster wheels larger than 2” in diameter x 2-3/4” wide. Each riser has a removable non slip gripper on bottom that stops furniture from sliding, protects floors from damage, and is safe on all hard floor surfaces and low pile carpet (not recommended for high pile carpet). To prevent any possible sliding of furniture on stack-its please use included adhesive non slip gripper pads. To add height to furniture, simply stack these interlocking risers on top of each other. Each Stack Its riser adds 1 inch height - max stack height is 3 inches / 3 stack-its (3" lift requires purchase of 2 sets). Not to be stacked higher than 3 inches, to raise furniture higher see Slipstick CB671 5” furniture risers. Includes 8 clear 4 inch round by 1 inch tall furniture risers with high weight capacity and non slip gripper pads for use between stack its and bottom of supported furniture. Each individual stack-it riser will support up to 1,000 pounds and are transparent for low visibility (Set of 4 will support 4,000 pounds).