dryer drum so the lower edge surfaces 122 124 of the side rails form the north and south poles respectively since the cross sectional area of the side rails taken in a horizontal plane extending longitudinally of the side rails is preferably less than the cross sectional area of the rectangular prism shaped magnet taken through a vertical plane extending longitudinally of the magnet the flux fields in the side rails are concentrated so the magnetic unit force by which the spoiler bar assembly adheres to the dryer drum is increased or at least not decreased thereby optimizing the strength of the magnet in other words within practical limits i e not making the rail edge surfaces extremely narrow if the cross sectional area of the side rails is less than or equal to the cross sectional area of the magnet or magnetic segment the unit magnetic force of attraction of the rail edge surfaces against the dryer drum is correspondingly greater than or equal to the unit strength of the magnet fig5 illustrates how the magnet 128 can comprise a plurality of similar magnetic segments 128 128a b c d e f g h aligned axially with their north and south pole faces aligned vertically on either side the lower edge 126 is straight because the lower surface of the magnet s is flat against the stainless steel base plate 121 which is spaced above the dryer drum surface to retard fringing of the magnetic flux lines.