When heat pressing fabrics with zippers, buttons, pockets, or any other uneven surfaces its best to use a teflonHeat Transfer Pillow. A teflon heat transfer pillow will raise the fabric to help avoid heavy seams and other uneven spots. Also its best to use as a insert for mesh and reversible jerseys. The heat transfer pillow is made with a 3/4" heat resistant foam covered with 3 mil teflon. It is re-useable and can be used on either side.