I bought and installed the filter two months ago!
It is ABOUT 0.01 and not 0.01 as they write, but since I don't have testers and I can tell from experience taste smell etc I want to emphasize that this water did not smell to me NOT ONCE in my bottle THAT'S IT this says it all for me.....of course I would like to test all this chemically etc but it takes extra money! so to everyone I would recommend if they want to have an under-sink single filter to get one, if not then at least 0.5μM! This one has final filtration and a diameter of about 0.03μM as you will read! I would definitely recommend it! I wish it were a little cheaper though but you get what you pay for, but be careful with filters this does not apply if you don't look into it carefully!!!Be careful with decimals 0.1 is different from 0.01 ! good shopping I wish!

Update: after almost 4 months no problem no smell everything perfect I got one for my parents and brother!
Update 30/10/21 I renewed the filter with the company's discount I am super satisfied, me and two other family homes, guys even until the change it was like new in taste, ten years I have been using filters I have never seen such a thing!

Update 1. (White filter) The company upgraded the filter and now the new primato ufc is 4 stages instead of 2. It has 2 stages of polypropylene 10 and 5 micro. 1 stage of 1 micron carbon and the membrane 0.01. The new filter is white and not yellow. And it is manufactured by a different company that is not Siam cast nylons in Thailand, but another Korean company. The original review of the old model follows.

(Yellow filter) The filter is 2 stages and is imported by only one company in Greece, primato. It is one of the few ultrafiltration filters available. Its permeability is 0.01 microns, which is so narrow and traps almost everything from harmful elements in the water. However, it is not so small as to retain natural minerals and water trace elements, so the water remains nutritious and unchanged. Ultrafiltration technology is one of the best methods of mechanical filtration. It has 10-micron external carbon to retain chlorine, heavy metals such as lead, cysts, cryptosporidia, sediment, etc. And inside it has hollow fiber membranes where the barbaric filtration takes place, cleaning the water from bacteria if present, and various microorganisms. To understand how small the pore size of the fiber filtration is, just think that a hair strand has a thickness of 100 microns and this filter has a pore size of 0.01. And bacteria, according to WQA, range from 1 to 0.2 microns, which means that the filter easily retains them. Also, to better understand the nominal filtration of the premium UFC 0.01, just think that the size of the Hepatitis B virus is approximately 0.04 microns, which means it is larger than the 0.01 of the filter, so it does not pass through. I have been confidently using this filter for a year now and I will probably choose it again. Also, the carbon used by the manufacturing company is NSF 42 certified.

For the old yellow model, the manufacturing company is Siam cast nylons in Thailand. And their website is carbonblocks.com.
Finally, for informational purposes, for those who purchase it and want to know more. I also requested the company from which I bought it to send me the certificates by email to see them, and they actually did. So if anyone wants to see them, they can request them. I also sent an email to the Asian company Siam cast nylon to confirm what the Greek store told me, and they responded the same. So go ahead and make your purchase without fear.