Opel ASTRA Owner's Manual page 46

44 Seats, restraints
Seat height
Lever pumping motion
up : seat higher
down : seat lower
Seat inclination
Press switch
top : front end higher
bottom : front end lower
Lumbar support
Adjust lumbar support using the four-
way switch to suit personal
requirements.
Moving support up and down: push
switch up or down.
Increasing and decreasing support:
push switch forwards or backwards.