Opel Automobile Owner's Manual page 48

48 Seats, restraints
Insignia OPC
Feed seat belt through belt mount on
backrest when fastening seat belt.
Height adjustment
1. Pull belt out slightly.
2. Press button.
3. Adjust height and engage.
Adjust the height so that the belt lies
across the shoulder. It must not lie
across the throat or upper arm.
Do not adjust while driving.