the radii r 1 and r 3 intersect at the centre point m of the cylinder 4 reference numeral 19 denotes the side screen the card flat bars 14 are extruded hollow profiles made of aluminium having an internal cavity 14 c fig3 a and 3 b show a first embodiment of card flat bar according to the invention the card flat clothing 24 consists of clothing tips 18 wire hooks and a supporting element 25 support layer made of a textile material the wire hooks 18 are approximately u shaped and punched through the surface 25 u2032 are fixed in the supporting element 25 the turn regions 18 u2032 see fig4 of the wire hooks 18 project beyond the surface 25 u2032 the ends of the wire hooks 18 the clothing tips are free the wire hooks 18 consist of steel wire two ribs 14 d 14 e are provided laterally on the card flat foot 14 a in the longitudinal direction so that in the region of the foot face there is a recess 14 f by means of which the card flat clothing 24 is held protected and embedded in the recess 14 f there is arranged a magnetic element 29 for example a magnetic tape magnetic strip magnetic bar or the like which is attached to the foot face by means of an adhesive layer 30 the magnetic element can also be formed on the card flat bar by casting compression moulding or the like for example magnetic powder with a curable resin the magnetic element.