Dürkopp Adler 868-M Operating Instructions Manual page 80

Operation
Fig. 53: Additional equipment seam middle guide (2)
②
(2) - Seam middle guide
To keep the seam middle guide (1)/(2) from leaving marks or
damaging the sewing material, the maximum operating pressure
must not exceed 3 bar.
78 Operating Instructions 868-M - 01.0 - 12/2020