Aston Martin DB11 Owner's Handbook Manual page 60

Seat Belt Fastening
When parked on an incline, the seat belt may lock as it is
withdrawn. This is not a fault. If the mechanism locks, release the
belt tension and then pull the belt very gently to avoid operation
of the inertia lock.
Each seat has three point, inertia reel seat belts installed. Items 1,
2 and 3 show the three points of the seat belt. Item 3 is also the
location of the belt buckle.
The inertia belt reels will automatically tension the belts to
provide security with comfort. In the event of a collision or during
severe braking, the belt reels will lock.
To test the locking function of the retractor, quickly pull the seat
belt forward. If the seat belt does not lock, consult your Aston
Martin dealer.
3.14
Before Driving
Pull out the seat belt, drawing the buckle over the shoulder and
across the chest.
Push the buckle into the belt buckle latch until a positive click is
heard.