You can put them on any type/size of pillow case that you can iron. It is generally recommended that you use a cotton or cotton/poly blend for transfers. Most of the designs are meant to be put around the edge of the pillow where you insert your pillowcase so that your child doesn't sleep on the design, and also so that they can take the pillowcase (minus pillow) to the park and have it autographed. You can resize the design to fit any size pillow from a baby size/airplane pillow to king size. Hope that is the information you are looking for!