guide roller 22 driving product strip 16 is for example driven by motor 29 on the shaft 30 which connects motor 29 with guide roller 22 a gear wheel 31 is fixed this gear wheel 31 meshes with a further gear wheel 32 which is fixed onto a shaft 34 which can rotate in a bearing fixed in frame 33 the wheel 12 can freely rotate in a bearing at one end of shaft 34 further a motor 35 is fixed onto gear wheel 32 to the shaft 36 of this motor a pinion wheel is fixed which is meshed with the internal teeth of wheel 12 when motor 29 is switched on it will directly rotate guide roller 22 which effectuates the transport of product strip 16 whilst gear wheel 32 with shaft 34 is rotated by gear wheel 31 when motor 35 is not energized shaft 36 and pinion wheel 37 will be stationary and wheel 12 will be rotated with a rotation speed equal to the rotation speed of shaft 34 whereby the perephiral velocity of wheel 12 and guide roller 22 are equal depending upon the signals obtained from sensors 27 and 28 can when a relative shift of position of masking belt 15 and product strip 16 is required motor 35 be energized to effect a displacement of wheel 12 rotating on shaft 34 with gear wheel 32 in one or the other direction so.