bar 33 are widened so that the support bar 33 reaches behind the support slot 24 this way it is not possible to lift the cutting slide 26 out of the support slot 24 the support bar 33 terminates slightly above a topside plane of the support wall 4 there a fixated cutting blade 34 that extends in a vertical plane is molded into the support bar 33 the cutting blade 34 extends into the groove recess 25 and is connected there with a slight base 36 which has a rectangular cross section the operating head 27 with the support bar 33 the cutting blade 34 and the slide base 36 form a rigid unit the cutting blade 34 extends in the illustration of fig3 perpendicular to the drawing plane and has sharp cutting edges at its front side and backside viewed in a direction of the support slot 24 at a side of the side lobe 11 that is oriented towards a viewer of fig1 and fig2 an adhesive tape dispenser 37 is attached the adhesive tape dispenser has a housing 38 into which an adhesive tape roll is inserted at a front side the housing 38 has a dispensing opening 39 through which an adhesive tape strip that is pulled.