The cup is fine, however the bubbler creates large, as opposed to fine, bubbles. Which did two things for me, compared to the bubbler in the cup from the rental. Because of the larger bubbles, it used at least double the amount of distilled water, and the line became wet often.
When the rental company picked up their condensor, they left the "one use" cup. I switched out them and and haven't looked back. Everyone is different, a higher humidity bubble may work better for another person.
The staff at OxygenPlusMedical have been fantastic to work with every time I've reached out to them, helpful and patient with spot on advice.
Thank you so much, have a great weekend!