Here is the link to the aquarium pharm website. It is called a 'tap water filter'. Photo is on the site.
http://www.aquariumpharm.com/productListing.html#T
Here is the write up:
An easy-to-use, single-cartridge tap water filtration system that removes impurities from tap water, making perfect, deionized aquarium water. Filter resin changes color when it's time to replace cartridge. Used cartridge can be replaced without tools in minutes. Comes fully assembled and attaches to any faucet in seconds. Includes faucet adapter and tubing. For freshwater, saltwater, African cichlid or community aquariums.