This is replacement media to refill the Whole House Water Filter 2-Media 1-Tank Filter for CHLORINE. (If you have chloramine, see that separate item.)
The choice you have is the option between raw media or a filled tank.
With raw media you need to remove the existing media and replace it with the new, as shown in included instructions. This is somewhat awkward, as the tank opening is small. But this is not a major challenge for a handy person. It can take a little while.
Otherwise, you can get a complete, full, filled replacement tank. With that option you just disconnect the older tank and attach the new one. If you wish, you can return the used tank to the factory for a $100 credit that will offset the cost of returning the tank for recycling.
This filter media should be changed every 600,000 gallons as of early 2017. Earlier models lasted less long, most recently 500,000. Follow original instructions. With this refill you can go 600,000 gallons before changing again.
The media included is both the patent-processed FOAM ADVANTAGE kdf and the granulated coconut carbon.
You may have a blue tank or one that looks like the cutaway picture. This is the right media in either case.
This whole house water filter replacement or refill does not include replacement filters for sediment pre-filters. Those normally are changed once a year. Purchase separately.