That mask has one serious draw back. You have to take it off to change the filters and they are not easy to change. It takes several minutes if you practice and are good at it.
I prefer something with an external filter so that if you have to change it in a contaminated environment you simply hold your breath unscrew the old one, screw the new one on clear your mask and continue about your business.
You are correct !
I, however, am government trained with tha M-17, and this is identical, but covers bio also.
At the price, buy several, and a change takes less then 15 seconds.
I have 6 of these, and 4 M-17 mask, including 30 and 60 filters.
They work, and for 12-14 hours of continuous exposeure.
If you do not have mop gear, and decontamination capability, everything is a waste.