The members of a shared transport group can work in shifts that begin and end at different times, but they should not deviate greatly or the shared transport group will become impractical. You are specifying the maximum allowable deviation in the schedule of each participant in the same shared transport group.
If you enable Shared Transport Constraints, this dialog box appears in place of the Team Synchronicity page (team restraints and shared transport group restraints are mutually exclusive). Type, or use the spinner controls, to specify the maximum allowable deviation between the start times and end times of shifts for the shared transport group members. You can specify any value between 1 minute and 23 hours, 59 minutes; most practical values will be less than 30 minutes.