Simply push and twist the knurled machined surface. They are designed for use in fuel or oil applications and are available in -6AN and/or -8AN flare fittings. The couplers have been successfully tested on Radium's test bench at 150psi engaged and disengaged.

The anodized aluminum fittings are available as a set (inner and outer) or as individual parts. 

If a step up (or down) in hose size is required, the -8AN and -6AN fittings are interchangeable and can be configured as shown below.

Important Notes:
-These fittings flow equally in both directions and can be installed either way.
-The higher the operating pressure, the more difficult it becomes to connect and disconnect the coupler.
-Due to the dry break coupler design, there will be some inherent flow restriction (pressure drop).
-Naturally there might be a drop when engaging and disengaging. 
-Do not disconnect fittings while pumps are running.

Technical Data:
-Overall length: -6AN kit = 82mm, -8AN kit = 87mm
-Weight: -6AN kit = 62g, -8AN kit = 69g
-Average pressure drop across coupler: 1-2psi
-Flow loss: 2% at 800LPH