[Liquidsand]

Hello all,
I have all the parts I need to couple my two concentrators except the equivalent of the green plastic "Christmas tree" that connects directly to the nipple on the second concentrator. I have read many times that these parts should be readily available at hardware stores, but everything I have tried just doesn't have the right threads, including a brass "NPT hose adaptor" that I ordered from ABR.
Does anyone have the specific part number and/or description of a fitting available at Home Depot or Lowe's, or is it true that my only option is to order the green plastic part from a medical supply (which means waiting another week)? Essentially, all I need is something that will attach one end of the viny hose to the concentrator securely.
Eternally grateful for any suggestions.
Martha