Back Up Second Stage:

The Back Up second stage is the Scubapro Alternate Inflator Regulator (AIR2), the only device connected to the Scubapro MK20 first stage.

The first generation AIR2 got a bad reputation after failing one of the US Navy certification tests. This is a third generation product and, if it were a no prejudice, stand alone regulator, it would be rated as a good main unit.

Using an AIR2 you must share your main second. This is better (there is a lot of stuff about this in the Hoggartian and DIR web sites).

LP Hose:

I use a 45 cm. (17,5 inches) low pressure hose. It is the original Scubapro hose you get when purchasing the AIR2, shortened by a local craftsman, cutting the first stage side.

The hose is directly routed along the corrugated, and held in place by one of the Halcyon original rubber rings.

Velcro strap:

The whole is secured to the left harness strap with a Velcro holder that, when closed makes a tight ring. I've made mine adapting a tie for organizing computer wires that I got from Ikea, but it is very easy to make one at home.

Velcro fitting:

The Velcro holder is fitted to the left strap with the original left shoulder D ring stopper (triglide fastener). The ring itself has been removed.