Product review (5 stars): Perfect replacement - great price!
I was so pleased to see these were available on Amazon. I had ordered them online before in other places, but not as cheap as this! Pricing is significantly better than buying in any retail store. Definitely worth picking up a multi-pack to save even more per filter. As far as I know there is no experation date on them...so they should be good for a long time.
  I have to replace mine maybe every 9 months or so, and I use it daily to fill two 32 oz. water bottles plus all the normal use at home. So easy to install - just be sure to run a few pitchers full of water through to flush out the filter and get the air out of the lines.