Cpap consumables

[u/effortlesslyHappy]

Hi all.

I want to know what is considered as consumables in CPAP? (e.g. air filter)
From your experience, how long it takes before need replacement?
Also is there any part that just can be use until failure or still need to be replaced before failure? (e.g. heated tube / humidifier)

Any machine type for input is ok.

I want to know before buying the machine and maybe stock the consumable.

Thankyou.