Yes they do work, I had one for years and gave it away.
Considering the strainers available today that one would not be
my 1st pick, maybe 6th or 7th.
It does work.
It is also fragile.
The filter does not last long and is tough to clean.
If you what a cartridge type then check out the Ceramic
types, they allow you to scrub the filter clean.
IMO the best bet for your hard earned $$ right now
are the Sawyer inline filters.

ALL filters, ALL makes require a decent pre-filter
and no one makes one, you must do that yourself.