GMC 2009 Sierra - Manual (Page 291)

Recovery Hooks
{ CAUTION:
These hooks, when used, are under a lot of
force. Always pull the vehicle straight out.
Never pull on the hooks at a sideways angle.
The hooks could break off and you or others
could be injured from the chain or cable
snapping back.
Notice: Never use recovery hooks to tow the
vehicle. Your vehicle could be damaged and it would
not be covered by warranty.
Your vehicle has recovery hooks at the front of the
vehicle. You can use them if you are stuck off-road and
need to be pulled to some place where you can
continue driving.
4-33