scott 30 minute tank

It's a SCBA adapter. There are several suppliers of the hose assemblies. 

CGA347 adapter. The wrench tighten version cost about $20 and the hand tighten version cost $40 and up for the adapter alone. If you don't mind buying Chinese you can get an entire fill assembly, everything you need to fill your PCP from the tank for $45. Other places like Airhog, AirTanksForSale will cost you about $150 plus shipping for entire fill assembly.

I have purchased both the china brands.in my opion,, they are great buys.