Texasguy
Contributor
I have a 40cu pony. When I come to fill a 130cu, I ask them to top off my pony. Most stores have no problem as loss usually attributed to some regulator squeezes on the surface and a few test breaths underwater, 200 PSI max after some number of dives. However, I also have a whip, this would allow me to take my high pressure tank and leak some into my 3Kpsi pony. The whip is $100 but when you need one, it is priceless. If you need to "leak" some cubic feet for your spare air, I'd get the whip.
(you can also find one with yoke connectors if you require such)
https://www.divegearexpress.com/dgx-gas-transfill-hose-with-analog-gauge
(you can also find one with yoke connectors if you require such)
https://www.divegearexpress.com/dgx-gas-transfill-hose-with-analog-gauge