a package liner adapted to protect fragile articles during shipment , handling and display in retail establishments . the liner is made of an elongated , flexible packaging material , such as a single face corrugated paper pad , having a pair of spaced , oppositely disposed , outwardly bowed lines of weakness impressed across its central width . when the ends of the liner are folded upwardly and flexed into a generally tubular conformation , the area between the lines of weakness assumes a downwardly concave shape . the resulting u - shaped structure is adapted to receive the article therewithin and cushion it against breakage when the package is dropped or exposed to lateral shock forces .