From its innovative use of Timestrip technology to the new patented carbon filter carrier, every new feature has been designed with simplicity and convenience in mind. This is truly the intuitive filtration system. Simple Set Up -- Ready to go right out of the box. No priming required; Simple Operation -- Patented Timestrip technology lets you see at a glance when its time to replace your carbon filter; Scientifically Engineered Water Flow -- Continuous flushing action prevents debris build up. Outflow maximizes water agitation and oxygenation. Whisper EX Filtration Systems use Tetra carbon filters . Timestrip Cartridge Change indicator included.