Product review (1 stars): This is a scam as several other reviewers noticed. ...
This is a scam as several other reviewers noticed. First, the "Blue Signature" water filter claims a NSF testing for both NSF 42 & 53. Looking up the NSF database shows no product certification for "Blue Signature". You can check it on the info-nfs-org website.

In addition, the brand "Blue Signature" claims to be trademarked "TM" but it is not. A trademark search only shows Colgate-Palmolive as a registrant for a personal care product by the name "Blue Signature". You can check it on the USPTO-TESS database.