...if ya want a direct tube to breathe through, any mask will do by just pulling tube connector off mask...cutting off if ya hafto. i couldn't do because it was uncomfortable and the pressure of the mask, CRAMMED into my face, actually helped. just be sure to plug/squeeze nose so you are getting pure O2 only...which is critical....
...btw...if you got a typical nonrebreather be sure to tape shut those dang holes on the side...a slight lift off the chin to exhale worked best for me...
j