[Widely Used Rubber Wheels] Pulleys are great for reducing your labor and relaxing your life. These sticky wheels make it easier to slide storage boxes, shoe racks, litter boxes, buckets, DIY baby toy cars and more.[Tool-free installation of small wheels] These small wheels are easy to install without using additional tools. 1. Wipe the bottom of the box. 2. Remove the release liner from each adhesive caster. 3. Glue the rubber wheels to the corners of the bottom,generally 4 are enough. 4. Make sure the rubber wheel is well fixed on the box, then you can make a removable box.[High Quality Moving Effect] These 20 pieces are available as 5 sets for your home and office use. 4pcs sticky casters can be attached as a set to the bottom of a box or board or machine base.They are made of high quality plastic material, no metal inside, more scientific and will not scratch the contact surface.[Safe for Parent-Child Play] These sticky casters are a fun accessory for kids to play with their parents (not alone) for DIY rolling trains, trucks, removable cartons, and more. Children will learn to move and control little things on their own, withjoy.