Hayes Nine Bleed Fitting?

[Flat Broke]

Is the sliver aluminum fitting from Hayes required to bleed the HFX Nine brakes? Obviously I don't want to puke fluid out of the lever all over everything, but is the silver fitting a small check valve or is it just an adapter to get a hose into the bleed hole so that fluid can drain cleanly into a catch bottle for inspection for bubbles etc?
The syringe and hose isn't a problem, and I understand the procedure, but I was curious about the fitting.
My rear is a little soggy, and probably needs a fluid change, so if I need to buy the fitting b4 I start it'd be good to know.
Thanks in advance,
Chris