GMC Sierra Denali Owner's Manual page 121

A. Back rail
B. Side rail
C. Rear bow
D. Center bow
E. Front bow
F. Front rail
2. Remove the tonneau cover from the notch in the
front rail on the driver's side of the vehicle.
3. Remove the three bows by gently pushing them
against the spring-loaded end. The three bows
are labeled front, center, rear
to
remind you of the
order in which to reinstall them.
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