is a German national organization for standardization from which the modern types and sizes of scuba connector hardware takes its name. Thes are modern direct screw-in connectors.

• Pressure gauge – In order to monitor breathing and gas pressure in the diving cylinder a diving regulator with a high pressure hose leads to a content or ‘pressure’ gauge which then reads the amount of pressure in the system. This is important as the diver will use this info to determine how much useable air is left in the tank.

Standard Pressure gauges- Standard pressure gauges are analog gauges that are held in the palm of the hand and are connected the first stage by a high pressure hose.

Button Gauges – Button gauges connect directly to the first stage and are often used on decompression cylinders. These can be a little difficult to read as they are typ0cically quite small in size.

Air Integrated Computers – These are great for more application and reading options when it comes to an updated diving cylinder pressure reading, but these should always be backed up with a standard air pressure gauge of some kind.

Mechanical Reserve Valves

Throughout diving history there are some types of cylinders that use mechanical valves that restrict the flow of air when the pressure is below a particular amount. These are known sa ‘j valves’ because the letter ‘J’ is next to the valve in U.S. diving catalogs.

Valve without the reserve lever are called ‘K valves’ for similar reasons. Modern diving equipment features J valves with a reserve valve in the open position. Such typical setups would also need to depend on a contents gauge or computer in order to accurately monitor gas supply.