Product review (5 stars): Quality product, easy to install.
Works great as a replacement right out of the box.  Arrived securely packed and protected and fit perfectly in the humidifier for which it's designed.  Don't be mis-led by the photo.  The actual filter has a sturdy plastic "frame" around it for protection and support, just like the original.  It's easy to self-install and snaps right in.  Note:  it's helpful to have a shop-vac or dust-buster around to clean up the dried calcium and dust that collects below the pad that's being replaced.