The TruXedo^® Lo Pro QT tonneau cover has automatic tension control. There are two spring loaded steel plungers at the front of the bed that maintain constant tension on the front header, allowing the cover to stay tight in any weather. Initially, you need to set the tension. This should be done during the warmest part of the day by closing the cover, releasing the Velcro^® brand fasteners from both sides near the cab, and checking compression of the spring plungers against the front header. Roll cover open to make adjustments. Repeat until satisfactory tension is achieved. Refer to the TruXedo^® Lo Pro QT Owners Manual for more specific information.