Markings can vary for place to place and should not be ignored if they seem unfamiliar. The S80 on the side of a cylinder indicates the internal capacity of the tank - 80 Cubic Feet/11. litres
This is important to know when planning dives as the gas available will be the pressure multiplied by the volume; for example - 200 bar x 11.1 litres means 2,220 litres of gas available for the diver at the beginning of the dive.
Take your PADI Divemaster training with Master Divers, Koh Tao. Thailand, and enjoy a day with our equipment technicians getting to know your way around equipment care and maintenance, including cylinder care.