I just did a quick online search and found two minor mentions of the filter. Both said it was a good filter. Unfortunately, they were not specific at all or I would have linked them.
Freedom is the sure possession of those alone who have the courage to defend it. -Pericles
Let every nation know, whether it wishes us well or ill, that we shall pay any price, bear any burden, meet any hardship, support any friend, oppose any foe to assure the survival and the success of Liberty -JFK