Chrysler 300 SRT8 Owner's Manual page 46

44 THINGS TO KNOW BEFORE STARTING YOUR VEHICLE
2. The seat belt latch plate is above the back of your seat.
Grasp the latch plate and pull out the belt. Slide the latch
plate up the webbing as far as necessary to make the belt
go around your lap.
Pulling Out the Lap/Shoulder Belt Latch Plate
3. When the belt is long enough to fit, insert the latch
plate into the buckle until you hear a "click."
Inserting Latch Plate into Buckle