Article reference KA-02056
Yes, the cylinder has an internal air bubble. For more information on recharging this, please see the below link.
SCx, SCxn Cylinders - Water can be seen running through the tundish
Applicable Models:
SCx Range - SCx130i SCx150d SCx175d SCx175sd SCx175si SCx215d SCx215i SCx215sd SCx215Ssi SCx255sd SCx255si SCx305sd SCx305si
SCxn Range - SCxn130d SCxn130i SCxn150d SCxn150i SCxn175d SCxn175i SCxn215d SCxn215i SCxn255d SCxn255i SCxn305d SCxn305i SCxn80d SCxn80i