Pressure Sensitive Adhesive (PSA) is thin, very flexible, and features a pressure-activated adhesive. Polyback is made from engineered material applied to a semi-rigid backer and is installed using contact adhesive. PSA is commonly used to apply a matching finish to face frames and other visible parts of the cabinet box during Refacing, and Polyback is commonly used instead of PSA when a more rigid material is needed, such as for worn cabinet boxes, or around islands.