The rear armrest in the center of the rear seatback can be used (no occupant in the center seat) or placed upright.

WARNING
Never put your hands and fingers around the moving parts of the seat and armrest:
Putting your hands and fingers around the moving parts of the seat and armrest is dangerous as they could get injured.
Split Folding
Head RestraintsMazda 6 Owners Manual: Glass panel adjustment
1. Fully close the glass panel.
2. Measure the gap and height between the glass panel and body.
3. If not as specified, loosen the glass panel installation screws and
reposition the glass panel.
Clearance
a: -0.8-1.2 mm {-0.032-0.047 in}
b: 0 mm {0 in}
4. Tighten the installation scre ...
Mazda 6 Owners Manual: Sst
Some Ford SST or equivalent are used as SSTs necessary for
engine repair. Note that these SSTs are marked with Ford SST
numbers.
Note that a Ford SST number is written together with a
corresponding Mazda SST number as shown below.
Example (section ST)
Example (except section ST)
...