This instructional video explains the differences between the three different types of scuba diving octos (backup regulators). It talks about the standard octo with a hose, an inline octo, and an integrated octo.
This video also shows how to attach the octopuses to your scuba diving BCD (Buoyancy Compensator Device) so you´re ready to dive.
The integrated octopus becomes your power inflator and your secondary breathing apparatus in the event of an emergency, while your second stage becomes your buddy´s. The standard octo in an emergency would go to your buddy and you would keep your second stage. The benefit of having an integrated or inline octo would be to remove a hose and streamline your scuba setup.