This machine has a precision of +/- 0,01 mm for tightening screws along the PVC profile. drylin® linear guides ensure the precise movement of the wrench along the profiles. In contrast to conventional ball bearings, these can operate in an environment heavily polluted by PVC sawdust and dust. More than a million screws have been tightened by this machine as of today. The bearings and linear guides have so far never needed to be replaced or serviced.