second side surface 20 cf fig8 the latching elements 34 36 are each arranged with the spring webs 70 72 thereof at a lower end of the form fitting element 62 which end faces away from the lower side 60 the latching elements 34 36 are arranged along a mirror plane of symmetry of the form fitting element 62 on both sides of the form fitting element 62 fig7 shows a mounting step of the adapter unit 14 onto the base unit 10 when the adapter unit 14 is mounted onto the base unit 10 the form fitting element 62 of the adapter unit 14 is introduced into the form fitting recess 16 of the base unit 10 either in the direction 30 or in the direction 32 for this purpose the spring web 70 72 of the respective latching element 34 36 first of all has to be deformed in the direction of the lower side 60 of the carrier plate 51 of the adapter unit 14 as soon as the form fitting element 62 is pushed centrally into the form fitting recess 16 the respective latching element 34 36 latches on the respective side surface 18 20 of the base unit 10 cf fig8 fig7 furthermore shows two spoiler elements 82 84 of the wiper blade 38 in the mounted state the spoiler elements 82 84 are pushed on both sides onto.