The Ocean Pro 6 Inch HP Hose is a short high pressure hose used to connect a transmitter on to the 1st of your regulator. This allows the transmitter to hang down to keep out of the way. Many divers pick up gear via the 1st stage and when a transmitter is attached, it can damage the connection. When a short hose is connected, this eliminates any damage. When you purchase a transmitter, you generally get a spool which sits between the transmitter and the hose. You can purchase these separately. The 6" hose is a braided material 3 times stronger than the rubber style hoses.