Product review (1 stars): no writing on this one and it seems to be working fine. My conclusion
I ordered these a few months ago and finally had a chance to use one.  I unwrapped it from the factory packaging but noticed that there was a date written on it using  a 'sharpie' type pen. It said 10-2-14.  Ok, maybe that was a manufacturing mark.  I twist it on and it leaks from the get go.  I try taking it off and reinstalling it...same thing.  Put a pan under it to catch the leak thinking that it may stop itself.....no go.
Since I had three, I decided to use another one....no writing on this one and it seems to be working fine.  My conclusion:  Some poor schmuck like myself bought this filter.  It leaked from the factory.  He sent it back and go a refund.  The fine folks at the factory tried to wash off the date but to no avail...Oh well, we will just rewrap it and send it out to some other schmuck.
Don't need to go any further with this. You can draw your own conclusion.